#include <bits/stdc++.h>
#pragma GCC optimize("-O3")
using namespace std;
void _main();
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  _main();
}
const int inf = INT_MAX / 2;
const long long infl = 1LL << 60;
template <class T>
bool chmax(T &a, const T &b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
  if (b < a) {
    a = b;
    return 1;
  }
  return 0;
}
struct SuperCombination2 {
  int mod, n, tot;
  vector<int> inv, fac, p;
  vector<vector<int>> t;
  int isinit = 0;
  int phi(int k) {
    int s = k;
    for (int i = 2; i * i <= k; i++) {
      if (k % i == 0) s = s / i * (i - 1);
      while (k % i == 0) k /= i;
    }
    if (k > 1) s = s / k * (k - 1);
    return s;
  }
  int fastpow(int a, long long b) {
    int res = 1;
    while (b) {
      if (b & 1) res = (1LL * res * a) % mod;
      b >>= 1;
      a = (1LL * a * a) % mod;
    }
    return res;
  }
  void init(int _n, int _mod) {
    mod = _mod;
    n = _n + 5;
    tot = 0;
    inv.resize(n);
    fac.resize(n);
    p.resize(n);
    t.resize(n, vector<int>(20));
    long long x = mod;
    int Phi = phi(mod);
    for (int i = 2; 1LL * i * i <= x; i++) {
      if (x % i) continue;
      while (x % i == 0) x /= i;
      p[++tot] = i;
    }
    if (x > 1) p[++tot] = x;
    inv[0] = inv[1] = 1;
    fac[0] = fac[1] = 1;
    for (int i = 2; i < n; i++) {
      x = i;
      for (int j = 1; j <= tot; j++) {
        t[i][j] = t[i - 1][j];
        if (x % p[j]) continue;
        while (x % p[j] == 0) x /= p[j], t[i][j]++;
      }
      fac[i] = (1LL * fac[i - 1] * x) % mod;
      inv[i] = fastpow(fac[i], Phi - 1);
    }
    isinit = 1;
  }
  int C(int n, int m) {
    assert(isinit == 1 && "Please init!!");
    int res = 0;
    if (n < m) return 0;
    if (m == 0) return 1;
    res = ((1LL * fac[n] * inv[m]) % mod * inv[n - m]) % mod;
    for (int i = 1; i <= tot; i++)
      res = (1LL * res * fastpow(p[i], t[n][i] - t[m][i] - t[n - m][i])) % mod;
    return res;
  }
};
int N, P, L, R;
void _main() {
  cin >> N >> P >> L >> R;
  SuperCombination2 sc;
  sc.init(N, P);
  int ans = 0;
  for (int i = 0; i < N + 1; i++) {
    int m = N - i;
    int d = (sc.C(m, (m + L + 1) / 2) - sc.C(m, (m + min(R, m)) / 2 + 1)) % P;
    ans = ((1LL * sc.C(N, i) * d) + ans) % P;
  }
  cout << ans << endl;
}
