func_code_string: #include <bits/stdc++.h>   using namespace std;   mt19937 rng(std::chrono::duration_cast<std::chrono::nanoseconds>(                   chrono::high_resolution_clock::now().time_since_epoch())                   .count());   const long long int N = 20005;   const long long int LG = 22;   long long int n, m;   long long int power(long long int x, long long int y, long long int m) {     if (y == 0) return 1;     long long int p = power(x, y / 2, m) % m;     p = (p * p) % m;     return (y % 2 == 0) ? p : (x * p) % m;   }   long long int fact[N], ifact[N];   void proecss() {     fact[0] = 1;     for (long long int i = 1; i < N; i++)       fact[i] = (fact[i - 1] * i) % 1000000007;     for (long long int i = 0; i < N; i++)       ifact[i] = power(fact[i], 1000000007 - 2, 1000000007);   }   long long int nCr(long long int n, long long int r) {     if (r > n) return 0;     if (r == n) return 1;     long long int ans = (ifact[n - r] * ifact[r]) % 1000000007;     ans = (ans * fact[n]) % 1000000007;     return ans;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     proecss();     cin >> n >> m;     long long int b[n + 5], a[n + 5];     for (long long int i = 1; i <= n; i++) {       long long int nn = n - i + 1;       long long int rr = m - 1;       b[i] = nCr(nn + rr - 1, rr);       a[i] = nCr(i + rr - 1, rr);     }     for (long long int i = n - 1; i >= 1; i--)       b[i] += b[i + 1], b[i] %= 1000000007;     long long int ans = 0;     for (long long int i = 1; i <= n; i++) {       ans = (ans + (a[i] * b[i]) % 1000000007) % 1000000007;     }     cout << ans << endl;     return 0;   }   