#include <bits/stdc++.h>
using namespace std;
const int Imx = 2147483647;
const long long Lbig = 2e18;
int mod;
struct fastio {
  char s[100000];
  int it, len;
  fastio() { it = len = 0; }
  inline char get() {
    if (it < len) return s[it++];
    it = 0;
    len = fread(s, 1, 100000, stdin);
    if (len == 0)
      return EOF;
    else
      return s[it++];
  }
  bool notend() {
    char c = get();
    while (c == ' ' || c == '\n') c = get();
    if (it > 0) it--;
    return c != EOF;
  }
} _buff;
inline long long getnum() {
  long long r = 0;
  bool ng = 0;
  char c;
  c = _buff.get();
  while (c != '-' && (c < '0' || c > '9')) c = _buff.get();
  if (c == '-') ng = 1, c = _buff.get();
  while (c >= '0' && c <= '9') r = r * 10 + c - '0', c = _buff.get();
  return ng ? -r : r;
}
template <class T>
inline void putnum(T x) {
  if (x < 0) putchar('-'), x = -x;
  register short a[20] = {}, sz = 0;
  while (x) a[sz++] = x % 10, x /= 10;
  if (sz == 0) putchar('0');
  for (int i = sz - 1; i >= 0; i--) putchar('0' + a[i]);
}
inline char getreal() {
  char c = _buff.get();
  while (c <= 32) c = _buff.get();
  return c;
}
long long qpow(long long x, long long k, long long md) {
  return k == 0 ? 1 : qpow(x * x % md, k >> 1, md) * (k & 1 ? x : 1) % md;
}
struct Combinactorial {
  static const int comb_mxn = 200111;
  int mod, phi_mod;
  int pn, pr[20], ppw[20][comb_mxn];
  int fac[comb_mxn], pcnt[comb_mxn][20];
  void initmod(int x) {
    mod = x;
    pn = 0;
    phi_mod = x;
    for (int i = 2; i <= x;) {
      i = x / (x / i);
      if (x % i == 0) {
        phi_mod = phi_mod / i * (i - 1);
        while (x % i == 0) {
          x /= i;
        }
        pr[pn] = i;
        ppw[pn][0] = 1;
        for (int j = 1; j < comb_mxn; j++)
          ppw[pn][j] = 1ll * ppw[pn][j - 1] * i % mod;
        pn++;
      }
      i++;
    }
    fac[0] = 1;
    for (int i = 1; i < comb_mxn; i++) {
      x = i;
      for (int j = 0; j < pn; j++) {
        pcnt[i][j] = pcnt[i - 1][j];
        while (x % pr[j] == 0) x /= pr[j], pcnt[i][j]++;
      }
      fac[i] = 1ll * fac[i - 1] * x % mod;
    }
  }
  int C(int x, int y) {
    if (x < y) return 0;
    int ret = 1ll * fac[x] *
              qpow(1ll * fac[y] * fac[x - y] % mod, phi_mod - 1, mod) % mod;
    for (int i = 0; i < pn; i++)
      ret = 1ll * ret * ppw[i][pcnt[x][i] - pcnt[y][i] - pcnt[x - y][i]] % mod;
    return ret;
  }
} cmb;
int n;
long long solve(long long l) {
  long long ret = 0;
  for (int i = 0; i <= n; i++) {
    if ((i + l) % 2 == 0) {
      int x = (i + l) / 2;
      ret += 1ll * cmb.C(i, x) * cmb.C(n, i) % mod;
    }
  }
  return ret % mod;
}
int main() {
  int l, r;
  cin >> n >> mod >> l >> r;
  cmb.initmod(mod);
  long long ans;
  if (l == r) {
    ans = solve(l);
    ans -= solve(l + 2);
  } else {
    ans = solve(l) + solve(l + 1);
    ans -= solve(r + 1) + solve(r + 2);
  }
  ans = (ans % mod + mod) % mod;
  cout << ans << endl;
  return 0;
}
