#include <bits/stdc++.h>
using namespace std;
const long long int inf = 1000000000;
const long long int mod = 1000000000 + 7;
inline void IO() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
inline int dcmp(long double x) { return x < -1e-12 ? -1 : (x > 1e-12); }
template <class T>
inline int CHECK(T MASK, int i) {
  return (MASK >> i) & 1;
}
template <class T>
inline T ON(T MASK, int i) {
  return MASK | (T(1) << i);
}
template <class T>
inline T OFF(T MASK, int i) {
  return MASK & (~(T(1) << i));
}
template <typename T>
inline int CNT(T MASK) {
  if (numeric_limits<T>::digits <= numeric_limits<unsigned int>::digits)
    return __builtin_popcount(MASK);
  else
    return __builtin_popcountll(MASK);
}
template <class T>
inline int RIGHT(T MASK) {
  return log2(MASK & -MASK);
}
int dx4[] = {0, 0, -1, +1};
int dy4[] = {+1, -1, 0, 0};
int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1, 0};
int dy8[] = {0, 1, 1, 1, 0, -1, -1, -1, 0};
inline void I(int& a) { scanf("%d", &a); }
inline void I(long long int& a) { scanf("%I64d", &a); }
inline void I(unsigned long long int& a) { scanf("%I64u", &a); }
inline void I(char* a) { scanf("%s", a); }
char Iarr[2000010];
inline void I(string& a) {
  scanf("%s", Iarr);
  a = Iarr;
}
template <typename T, typename... Args>
void I(T& a, Args&... args) {
  I(a);
  I(args...);
}
inline void OUT(int a) { printf("%d", a); }
inline void OUT(long long int a) { printf("%I64d", a); }
inline void OUT(const char* a) { printf("%s", a); }
inline void OUT(char* a) { printf("%s", a); }
inline void OUT(bool a) { printf("%d", a); }
inline void OUT(string a) {
  for (__typeof(a.end()) it = (a.begin()) - ((a.begin()) > (a.end()));
       it != (a.end()) - ((a.begin()) > (a.end()));
       it += 1 - 2 * ((a.begin()) > (a.end())))
    printf("%c", *it);
}
inline void OUT(unsigned long long int a) { printf("%I64u", a); }
template <typename T, typename... Args>
void OUT(T a, Args... args) {
  OUT(a);
  OUT(" ");
  OUT(args...);
}
template <typename... Args>
void O(Args... args) {
  OUT(args...);
  OUT("\n");
}
template <typename T1, typename T2>
inline ostream& operator<<(ostream& os, pair<T1, T2> p) {
  os << "{" << p.first << ", " << p.second << "}";
  return os;
}
template <typename T>
inline ostream& operator<<(ostream& os, vector<T>& a) {
  os << "[";
  for (int i = 0; i < (int)a.size(); i++) {
    if (i) os << ", ";
    os << a[i];
  }
  os << "]";
  return os;
}
void err(istream_iterator<string> it) {}
template <typename T, typename... Args>
void err(istream_iterator<string> it, T a, Args... args) {
  cout << *it << " = " << a << endl;
  err(++it, args...);
}
const int M = 200010;
struct NCRMOD {
  int n, MOD, PHI, residue[100001], fact[100001], inv_fact[100001];
  vector<int> primeDivisors;
  vector<vector<int> > C, P;
  int ModExp(int a, int n) {
    long long x = a % MOD, y = 1 % MOD;
    while (n) {
      if (n % 2) y = (x * y) % MOD;
      x = (x * x) % MOD;
      n /= 2;
    }
    return (int)y;
  }
  int ModInv(int a) { return ModExp(a, PHI - 1); }
  void PreProcess() {
    int m = MOD;
    for (int i = 2; i * i <= m; ++i) {
      if (m % i == 0) {
        while (m % i == 0) m /= i;
        primeDivisors.push_back(i);
      }
    }
    if (m > 1) primeDivisors.push_back(m);
    m = primeDivisors.size();
    C.resize(m);
    P.resize(m);
    fact[0] = 1, inv_fact[0] = 1;
    for (int i = 1; i <= n; ++i) residue[i] = i;
    PHI = MOD;
    for (int i = 0; i < m; ++i) {
      int p = primeDivisors[i];
      PHI /= p;
      PHI *= (p - 1);
      C[i].resize(n + 1);
      for (int j = p; j <= n; j += p) {
        int x = residue[j], k = 0;
        while (x % p == 0) {
          x /= p;
          ++k;
        }
        residue[j] = x;
        C[i][j] = k;
      }
      for (int j = 1; j <= n; ++j) C[i][j] += C[i][j - 1];
      P[i].resize(C[i][n] + 1);
      P[i][0] = 1 % MOD;
      for (int j = 1; j < P[i].size(); ++j)
        P[i][j] = (1ll * p * P[i][j - 1]) % MOD;
    }
    for (int i = 1; i <= n; ++i)
      fact[i] = (1ll * residue[i] * fact[i - 1]) % MOD;
    inv_fact[n] = ModInv(fact[n]);
    for (int i = n - 1; i > 0; --i)
      inv_fact[i] = (1ll * residue[i + 1] * inv_fact[i + 1]) % MOD;
  }
  int NCR(int n, int r) {
    if (n < 0 || r < 0 || n < r)
      return 0;
    else {
      long long ans = fact[n];
      ans = (ans * inv_fact[r]) % MOD;
      ans = (ans * inv_fact[n - r]) % MOD;
      for (int i = 0; i < primeDivisors.size(); ++i) {
        int c = C[i][n] - C[i][r] - C[i][n - r];
        ans = (ans * P[i][c]) % MOD;
      }
      return (int)ans;
    }
  }
} obj;
long long int func(long long int n, long long int sum, long long int MOD) {
  long long int ret;
  if (n % 2 == 0)
    ret = obj.NCR(n, n / 2) - obj.NCR(n, n / 2 + sum / 2 + 1);
  else {
    if (sum % 2 == 0)
      ret = obj.NCR(n, n / 2) - obj.NCR(n, n / 2 - sum / 2);
    else
      ret = obj.NCR(n, n / 2) - obj.NCR(n, n / 2 - sum / 2 - 1);
  }
  return ret;
}
long long int range(long long int n, long long int l, long long int r,
                    long long int MOD) {
  long long int ret = func(n, r, MOD);
  if (l > 0) ret -= func(n, l - 1, MOD);
  ret %= MOD;
  ret = (ret + MOD) % MOD;
  return ret;
}
int main() {
  long long int n, p, l, r;
  I(n, p, l, r);
  obj.MOD = p;
  obj.n = n;
  obj.PreProcess();
  long long int ans = 0;
  for (long long int i = l; i <= n; i++) {
    long long int temp = obj.NCR(n, i);
    temp %= p;
    temp *= range(i, l, r, p);
    temp %= p;
    ans += temp;
    ans %= p;
  }
  O(ans);
  return 0;
}
