#include #define ADD(a, b) a = (a + ll(b)) % mod #define MUL(a, b) a = (a * ll(b)) % mod #define MAX(a, b) a = max(a, b) #define MIN(a, b) a = min(a, b) #define rep(i, a, b) for(int i = int(a); i < int(b); i++) #define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--) #define all(a) (a).begin(), (a).end() #define sz(v) (int)(v).size() #define pb push_back #define sec second #define fst first #define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__) using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair pi; typedef pair pl; typedef pair ppi; typedef vector vi; typedef vector vl; typedef vector mat; typedef complex comp; void Debug() {cout << '\n'; } templatevoid Debug(FIRST arg, REST... rest){ cout<ostream& operator<<(ostream& out,const vector& v) { out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<ostream& operator<<(ostream& out,const pair& v){ out<<"("<= b if(a < b || a < 0 || b < 0) return 0; return fac[a] * fiv[b] % mod * fiv[a - b] % mod; } int N, M, L, R; void solve() { cin >> N >> M >> L >> R; C_init(1400000); int O = M - (N - 1) * L - 1; if(O < 0) { cout << 0 << "\n"; return; } ll res = 0; rep(p, 0, N) { ll l = O - 1ll * p * (R - L + 1); if(l < 0) continue; if(p % 2 == 0) { ADD(res, C(N - 1, p) * C(l + N, N) % mod); } else { ADD(res, mod - C(N - 1, p) * C(l + N, N) % mod); } } cout << res << "\n"; } int main() { #ifndef LOCAL ios::sync_with_stdio(false); cin.tie(0); #endif cout << fixed; cout.precision(20); srand((unsigned int)time(NULL)); #ifdef LOCAL //freopen("in.txt", "wt", stdout); //for tester freopen("in.txt", "rt", stdin); #endif solve(); #ifdef LOCAL cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n"; #endif return 0; }