#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
long long P[12], phi, nrp;
long long N, MOD, l, r;
void setMod(long long MOD) {
  phi = MOD;
  nrp = 0;
  for (long long i = 2; 1LL * i * i <= MOD; i++) {
    if (MOD % i == 0) {
      phi = (phi / i) * (i - 1);
      P[++nrp] = i;
      while (MOD % P[nrp] == 0) {
        MOD /= P[nrp];
      }
    }
  }
  if (MOD != 1) {
    P[++nrp] = MOD;
    phi = phi / MOD * (MOD - 1);
  }
}
long long lgpow(long long b, long long e) {
  long long p = 1;
  while (e) {
    if (e & 1) {
      p = 1LL * p * b % MOD;
    }
    b = 1LL * b * b % MOD;
    e >>= 1;
  }
  return p;
}
struct Integer {
  long long E[12];
  long long val;
  void init(long long x) {
    for (long long i = 0; i < 12; i++) {
      E[i] = 0;
    }
    for (long long i = 1; i <= nrp; i++) {
      E[i] = 0;
      while (x % P[i] == 0) {
        x /= P[i];
        E[i]++;
      }
    }
    val = x;
  }
  Integer operator*(const Integer &other) const {
    Integer ans;
    for (long long i = 0; i < 12; i++) {
      ans.E[i] = 0;
    }
    for (long long i = 1; i <= nrp; i++) {
      ans.E[i] = E[i] + other.E[i];
    }
    ans.val = (1LL * val * other.val) % MOD;
    return ans;
  }
  Integer operator/(const Integer &other) const {
    Integer ans;
    for (long long i = 0; i < 12; i++) {
      ans.E[i] = 0;
    }
    for (long long i = 1; i <= nrp; i++) {
      ans.E[i] = E[i] - other.E[i];
    }
    ans.val = (1LL * val * lgpow(other.val, phi - 1)) % MOD;
    return ans;
  }
  long long toInt() {
    long long rez = val;
    for (long long i = 1; i <= nrp; i++) {
      rez = 1LL * rez * lgpow(P[i], E[i]) % MOD;
    }
    return rez;
  }
};
Integer lgpow2(Integer b, long long e) {
  Integer p;
  p.init(1);
  while (e) {
    if (e & 1) {
      p = p * b;
    }
    b = b * b;
    e >>= 1;
  }
  return p;
}
Integer fact[100005];
Integer ifact[100005];
long long C(long long N, long long K) {
  if (K < 0 || K > N) {
    return 0;
  }
  return (fact[N] * ifact[K] * ifact[N - K]).toInt();
}
long long rez = 0;
int main() {
  cin >> N >> MOD >> l >> r;
  setMod(MOD);
  fact[0].init(1);
  for (long long i = 1; i <= N; i++) {
    Integer tmp;
    tmp.init(i);
    fact[i] = fact[i - 1] * tmp;
  }
  Integer tmp;
  tmp.init(1);
  ifact[N] = tmp / fact[N];
  for (long long i = N - 1; i >= 0; i--) {
    Integer tmp;
    tmp.init(i + 1);
    ifact[i] = ifact[i + 1] * tmp;
  }
  for (long long nonvip = l; nonvip <= N; nonvip++) {
    long long tmpans = C(N, nonvip);
    swap(N, nonvip);
    tmpans = ((long long)tmpans *
              ((C(N, (N - l) / 2) - C(N, (N - r + 1) / 2 - 1) + MOD) % MOD)) %
             MOD;
    swap(N, nonvip);
    rez = (rez + tmpans) % MOD;
  }
  cout << rez;
  return 0;
}
