description: Note that the memory limit in this problem is lower than in others.
  
  You have a vertical strip with n cells, numbered consecutively from 1 to n from top to bottom.
  
  You also have a token that is initially placed in cell n. You will move the token up until it arrives at cell 1.
  
  Let the token be in cell x > 1 at some moment. One shift of the token can have either of the following kinds: 
  
    * Subtraction: you choose an integer y between 1 and x-1, inclusive, and move the token from cell x to cell x - y. 
    * Floored division: you choose an integer z between 2 and x, inclusive, and move the token from cell x to cell ⌊ x/z ⌋ (x divided by z rounded down). 
  
  
  
  Find the number of ways to move the token from cell n to cell 1 using one or more shifts, and print it modulo m. Note that if there are several ways to move the token from one cell to another in one shift, all these ways are considered distinct (check example explanation for a better understanding).
  
  Input
  
  The only line contains two integers n and m (2 ≤ n ≤ 4 ⋅ 10^6; 10^8 < m < 10^9; m is a prime number) — the length of the strip and the modulo.
  
  Output
  
  Print the number of ways to move the token from cell n to cell 1, modulo m.
  
  Examples
  
  Input
  
  
  3 998244353
  
  
  Output
  
  
  5
  
  
  Input
  
  
  5 998244353
  
  
  Output
  
  
  25
  
  
  Input
  
  
  42 998244353
  
  
  Output
  
  
  793019428
  
  
  Input
  
  
  787788 100000007
  
  
  Output
  
  
  94810539
  
  Note
  
  In the first test, there are three ways to move the token from cell 3 to cell 1 in one shift: using subtraction of y = 2, or using division by z = 2 or z = 3.
  
  There are also two ways to move the token from cell 3 to cell 1 via cell 2: first subtract y = 1, and then either subtract y = 1 again or divide by z = 2.
  
  Therefore, there are five ways in total.
solution: #include <bits/stdc++.h>
  using namespace std;
  const long long MAXN = 1000005;
  const long long SQRTN = 1003;
  const long long LOGN = 22;
  const double PI = acos(-1);
  const long long INF = 1e18;
  const long long MOD = 1e9 + 7;
  const long long FMOD = 998244353;
  const double eps = 1e-9;
  void __print(long long x) { cerr << x; }
  void __print(long x) { cerr << x; }
  void __print(unsigned x) { cerr << x; }
  void __print(unsigned long x) { cerr << x; }
  void __print(unsigned long long x) { cerr << x; }
  void __print(float x) { cerr << x; }
  void __print(double x) { cerr << x; }
  void __print(long double x) { cerr << x; }
  void __print(char x) { cerr << '\'' << x << '\''; }
  void __print(const char *x) { cerr << '\"' << x << '\"'; }
  void __print(const string &x) { cerr << '\"' << x << '\"'; }
  void __print(bool x) { cerr << (x ? "true" : "false"); }
  template <typename T, typename V>
  void __print(const pair<T, V> &x) {
    cerr << '{';
    __print(x.first);
    cerr << ',';
    __print(x.second);
    cerr << '}';
  }
  template <typename T>
  void __print(const T &x) {
    long long f = 0;
    cerr << '{';
    for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
    cerr << "}";
  }
  void _print() { cerr << "]\n"; }
  template <typename T, typename... V>
  void _print(T t, V... v) {
    __print(t);
    if (sizeof...(v)) cerr << ", ";
    _print(v...);
  }
  mt19937 RNG(chrono::steady_clock::now().time_since_epoch().count());
  template <typename T>
  T gcd(T a, T b) {
    if (b == 0) return a;
    a %= b;
    return gcd(b, a);
  }
  template <typename T>
  T lcm(T a, T b) {
    return (a * (b / gcd(a, b)));
  }
  long long add(long long a, long long b, long long c = MOD) {
    long long res = a + b;
    return (res >= c ? res % c : res);
  }
  long long sub(long long a, long long b, long long c = MOD) {
    long long res;
    if (abs(a - b) < c)
      res = a - b;
    else
      res = (a - b) % c;
    return (res < 0 ? res + c : res);
  }
  long long mul(long long a, long long b, long long c = MOD) {
    long long res = (long long)a * b;
    return (res >= c ? res % c : res);
  }
  long long muln(long long a, long long b, long long c = MOD) {
    long long res = (long long)a * b;
    return ((res % c) + c) % c;
  }
  long long mulmod(long long a, long long b, long long m = MOD) {
    long long q = (long long)(((long double)a * (long double)b) / (long double)m);
    long long r = a * b - q * m;
    if (r > m) r %= m;
    if (r < 0) r += m;
    return r;
  }
  template <typename T>
  T binpow(T e, T n) {
    T x = 1, p = e;
    while (n) {
      if (n & 1) x = x * p;
      p = p * p;
      n >>= 1;
    }
    return x;
  }
  template <typename T>
  T binpow2(T e, T n, T m = MOD) {
    T x = 1, p = e;
    while (n) {
      if (n & 1) x = mul(x, p, m);
      p = mul(p, p, m);
      n >>= 1;
    }
    return x;
  }
  template <typename T>
  T extended_euclid(T a, T b, T &x, T &y) {
    T xx = 0, yy = 1;
    y = 0;
    x = 1;
    while (b) {
      T q = a / b, t = b;
      b = a % b;
      a = t;
      t = xx;
      xx = x - q * xx;
      x = t;
      t = yy;
      yy = y - q * yy;
      y = t;
    }
    return a;
  }
  template <typename T>
  T mod_inverse(T a, T n = MOD) {
    T x, y, z = 0;
    T d = extended_euclid(a, n, x, y);
    return (d > 1 ? -1 : sub(x, z, n));
  }
  const long long FACSZ = 1e4;
  long long fact[FACSZ], ifact[FACSZ];
  void precom(long long c = MOD) {
    fact[0] = 1;
    for (long long i = 1; i < FACSZ; i++) fact[i] = mul(fact[i - 1], i, c);
    ifact[FACSZ - 1] = mod_inverse(fact[FACSZ - 1], c);
    for (long long i = FACSZ - 1 - 1; i >= 0; i--) {
      ifact[i] = mul(i + 1, ifact[i + 1], c);
    }
  }
  vector<long long> primes;
  void prime_precom() {
    primes.push_back(2);
    for (long long x = 3; primes.size() <= MAXN; x += 2) {
      bool isPrime = true;
      for (auto p : primes) {
        if (x % p == 0) {
          isPrime = false;
          break;
        }
        if (p * p > x) {
          break;
        }
      }
      if (isPrime) {
        primes.push_back(x);
      }
    }
  }
  long long ncr(long long n, long long k) {
    if (n < k) return 0;
    if (k == 0) return 1;
    long long res = 1;
    if (k > n - k) k = n - k;
    for (long long i = 0; i < k; ++i) {
      res *= (n - i);
      res /= (i + 1);
    }
    return res;
  }
  long long ncr_modp(long long n, long long k, long long c = MOD) {
    if (n < k) return 0;
    if (k == 0) return 1;
    long long res = 1;
    if (k > n - k) k = n - k;
    for (long long i = 0; i < k; ++i) {
      res = mul(res, n - i, c);
      res = mul(res, binpow2(i + 1, c - 2, c), c);
    }
    return res;
  }
  vector<long long> factors;
  void factorize(long long a) {
    factors.clear();
    for (long long i = 1; i * i <= a; i++) {
      if (a % i == 0) {
        factors.push_back(i);
        factors.push_back(a / i);
      }
    }
    sort(factors.begin(), factors.end());
  }
  long long ncr_precom(long long n, long long r, long long c = MOD) {
    return mul(mul(ifact[r], ifact[n - r], c), fact[n], c);
  }
  long long ceil(long long a, long long b) { return (a + b - 1) / b; }
  bool is_prime(long long n) {
    for (long long i = 2; i * i <= n; i++) {
      if (n % i == 0) {
        return 0;
      }
    }
    return 1;
  }
  bool diophantine_checker(long long a, long long b, long long n) {
    for (long long i = 0; i * a <= n; i++) {
      if ((n - (i * a)) % b == 0) {
        return true;
      }
    }
    return false;
  }
  long long count_divisors(long long n) {
    long long c;
    long long ans = 1;
    for (long long i = 2; i * i <= n; i++) {
      c = 0;
      while (n % i == 0) {
        c++;
        n /= i;
      }
      ans *= (c + 1);
    }
    if (n > 2) {
      return ans * 2;
    }
    return ans;
  }
  string to_binary(long long n) {
    string r;
    while (n != 0) {
      r = (n % 2 == 0 ? "0" : "1") + r;
      n /= 2;
    }
    return r;
  }
  bool ispower2(long long x) { return x && (!(x & (x - 1))); }
  unsigned long long mulmodBitwise(unsigned long long a, unsigned long long b,
                                   unsigned long long p) {
    a %= p;
    b %= p;
    if (a <= 0xFFFFFFF && b <= 0xFFFFFFF) {
      return (a * b) % p;
    }
    if (b > a) {
      swap(a, b);
    }
    unsigned long long result = 0;
    while (a > 0 && b > 0) {
      if (b & 1) {
        result += a;
        result %= p;
      }
      a <<= 1;
      a %= p;
      b >>= 1;
    }
    return result;
  }
  unsigned long long mulmod2(unsigned long long a, unsigned long long b,
                             unsigned long long p) {
    a %= p;
    b %= p;
    if (a <= 0xFFFFFFF && b <= 0xFFFFFFF) {
      return (a * b) % p;
    }
    unsigned long long zeros = 0;
    unsigned long long m = p;
    while ((m & 0x8000000000000000ULL) == 0) {
      zeros++;
      m <<= 1;
    }
    unsigned long long mask = (1 << zeros) - 1;
    unsigned long long result = 0;
    while (a > 0 && b > 0) {
      result += (b & mask) * a;
      result %= p;
      b >>= zeros;
      a <<= zeros;
      a %= p;
    }
    return result;
  }
  unsigned long long powmod(unsigned long long base, unsigned long long exponent,
                            unsigned long long p) {
    unsigned long long result = 1;
    while (exponent > 0) {
      if (exponent & 1) {
        result = mulmod2(result, base, p);
      }
      base = mulmod2(base, base, p);
      exponent >>= 1;
    }
    return result;
  }
  vector<long long> spf;
  void sieve() {
    spf.resize(MAXN);
    spf[1] = 1;
    for (long long i = 2; i < MAXN; i++) {
      spf[i] = i;
    }
    for (long long i = 4; i < MAXN; i += 2) {
      spf[i] = 2;
    }
    for (long long i = 3; i * i <= MAXN; i++) {
      if (spf[i] == i) {
        for (long long j = i * i; j < MAXN; j += i) {
          if (spf[j] == j) {
            spf[j] = i;
          }
        }
      }
    }
  }
  void pfactor(long long x, vector<long long> &ret) {
    while (x != 1) {
      ret.push_back(spf[x]);
      x = x / spf[x];
    }
  }
  void solvethetestcase() {
    long long n, m;
    cin >> n >> m;
    vector<long long> dp(n + 1, 0ll);
    vector<long long> psum(n + 1, 0ll);
    vector<long long> upd(n + 1, 0ll);
    vector<long long> psm(n + 1, 0ll);
    for (long long i = 1; i <= n; i++) {
      psm[i] = psm[i - 1] + upd[i];
      psm[i] %= m;
      if (i == 1) {
        dp[i] = 1;
      } else {
        dp[i] = psm[i] + psum[i - 1];
        dp[i] %= m;
      }
      psum[i] = psum[i - 1] + dp[i];
      psum[i] %= m;
      for (long long j = 2; j * i <= n; j++) {
        upd[j * i] += dp[i];
        upd[j * i] %= m;
        if (j * (i + 1) <= n) {
          upd[j * (i + 1)] -= dp[i];
          upd[j * (i + 1)] += m;
          upd[j * (i + 1)] %= m;
        }
      }
    }
    cout << dp[n] << "\n";
  }
  signed main() {
    cout << fixed << setprecision(12);
    ;
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    long long t = 1;
    for (long long testcase = 1; testcase < t + 1; testcase++) {
      solvethetestcase();
    }
  }
  