#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:512000000")
using namespace std;
void solve(bool);
void precalc();
clock_t start;
int main() {
  start = clock();
  int t = 1;
  cout.sync_with_stdio(0);
  cin.tie(0);
  precalc();
  cout.precision(10);
  cout << fixed;
  int testNum = 1;
  while (t--) {
    solve(true);
  }
  cout.flush();
  return 0;
}
template <typename T>
T binpow(T q, T w, T mod) {
  if (!w) return 1 % mod;
  if (w & 1) return q * 1LL * binpow(q, w - 1, mod) % mod;
  return binpow(q * 1LL * q % mod, w / 2, mod);
}
template <typename T>
T gcd(T q, T w) {
  while (w) {
    q %= w;
    swap(q, w);
  }
  return q;
}
template <typename T>
T lcm(T q, T w) {
  return q / gcd(q, w) * w;
}
template <typename T>
void make_unique(vector<T>& a) {
  sort(a.begin(), a.end());
  a.erase(unique(a.begin(), a.end()), a.end());
}
template <typename T>
void relax_min(T& cur, T val) {
  cur = min(cur, val);
}
template <typename T>
void relax_max(T& cur, T val) {
  cur = max(cur, val);
}
void precalc() {}
const long long C = 100500;
long long mod;
long long phi;
long long rem[C];
long long rev_rem[C];
vector<long long> primes, degs;
long long n;
long long get_deg(long long n, long long p) {
  long long res = 0;
  while (n) {
    res += n / p;
    n /= p;
  }
  return res;
}
long long getC(long long n, long long k) {
  if (n < k) {
    return 0;
  }
  long long res = rem[n] * rev_rem[k] % mod * rev_rem[n - k] % mod;
  for (long long i = 0; i < primes.size(); ++i) {
    long long deg = get_deg(n, primes[i]) - get_deg(k, primes[i]) -
                    get_deg(n - k, primes[i]);
    res = res * binpow(primes[i], deg, mod) % mod;
  }
  return res;
}
long long get_res(long long l) {
  long long res = 0;
  for (long long par = 0; par < 2; ++par) {
    for (long long cur = 0; 2 * cur + par <= n; ++cur) {
      long long m = 2 * cur + par;
      long long cur_l = l;
      if ((cur_l + par) % 2) {
        ++cur_l;
      }
      long long now_c = (m + cur_l) / 2;
      res += getC(n, m) * getC(m, now_c);
      res %= mod;
    }
  }
  return res;
}
void solve(bool read) {
  long long l, r;
  cin >> n >> mod >> l >> r;
  rem[0] = 1;
  long long M = mod;
  phi = mod;
  for (long long p = 2; p * p <= M; ++p) {
    if (M % p == 0) {
      phi = phi * (p - 1) / p;
      primes.push_back(p);
      degs.push_back(0);
      while (M % p == 0) {
        M /= p;
        ++degs.back();
      }
    }
  }
  if (M > 1) {
    phi = phi * (M - 1) / M;
    primes.push_back(M);
    degs.push_back(1);
  }
  for (long long i = 1; i < C; ++i) {
    long long cur = i;
    for (long long p : primes) {
      while (cur % p == 0) {
        cur /= p;
      }
    }
    rem[i] = rem[i - 1] * cur % mod;
  }
  for (long long i = 0; i < C; ++i) {
    rev_rem[i] = binpow(rem[i], phi - 1, mod);
  }
  long long res = get_res(l) - get_res(r + 1);
  res %= mod;
  if (res < 0) {
    res += mod;
  }
  cout << res << endl;
}
