#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
long long p, n, l, r;
long long pr[N], inv[N], f[N], c[N][40], phi;
int cnt = 0;
long long powe(long long a, long long b) {
  long long base = 1;
  while (b) {
    if (b & 1) base = (base * a) % p;
    a = (a * a) % p;
    b >>= 1;
  }
  return base;
}
void calc() {
  f[0] = inv[0] = 1;
  f[1] = inv[1] = 1;
  long long x = p;
  for (long long i = 2; i * i <= x; i++) {
    if (x % i) continue;
    pr[++cnt] = i;
    while (!(x % i)) x /= i;
  }
  if (x > 1) pr[++cnt] = x;
  for (int i = 2; i <= n; i++) {
    long long x = i;
    for (int j = 1; j <= cnt; j++) {
      c[i][j] = c[i - 1][j];
      while (!(x % pr[j])) x /= pr[j], c[i][j]++;
    }
    f[i] = f[i - 1] * x % p;
    inv[i] = powe(f[i], phi - 1);
  }
}
long long comb(long long _n, long long m) {
  if (m < 0 || _n < m || n <= 0) return 0;
  if (m == 0) return 1;
  long long tmp = f[_n] * inv[m] % p * inv[_n - m] % p;
  for (int i = 1; i <= cnt; i++) {
    tmp = (tmp * powe(pr[i], c[_n][i] - c[m][i] - c[_n - m][i])) % p;
  }
  return tmp;
}
int main() {
  scanf("%lld%lld%lld%lld", &n, &p, &l, &r);
  phi = p;
  long long d = p;
  for (long long i = 2; i * i <= d; i++) {
    if (d % i) continue;
    phi = phi / i * (i - 1);
    while (!(d % i)) d /= i;
  }
  if (d > 1) phi = phi / d * (d - 1);
  calc();
  long long ans = 0;
  r = min(n, r);
  for (long long i = 0; i <= n - l; i++) {
    long long tmp = (comb(n - i, (n - i - l) >> 1) -
                     comb(n - i, (n - i - r - 1) >> 1) + p) %
                    p;
    ans += (tmp * comb(n, i)) % p;
    ans = ans % p;
  }
  printf("%lld", ans);
  return 0;
}
