#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; long long fac[10000020], finv[10000020], inv[10000020]; long long mod = 1000000007; void COMinit() { fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (int i = 2; i < 10000020; i++) { fac[i] = fac[i - 1] * i % mod; inv[i] = mod - inv[mod % i] * (mod / i) % mod; finv[i] = finv[i - 1] * inv[i] % mod; } } long long COM(long long n, long long k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % mod) % mod; } int main() { long long n, m; cin >> n >> m; long long ans = 0; COMinit(); for (int i = n; i <= m; i++) { ans += COM(i, n); ans %= 1000000007; } cout << ans << endl; return 0; }