func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 2019, mod = 998244353;   int n, m, ans, f[N << 1][N], g[N << 1][N];   int qpow(int a, int b) {     int ret = 1;     while (b) {       if (b & 1) ret = 1ll * ret * a % mod;       a = 1ll * a * a % mod, b >>= 1;     }     return ret;   }   int main() {     scanf( %d%d%d , &n, &m, &ans);     f[0][0] = 1;     for (int i = 1; i <= 2 * n; i++)       for (int j = 0; j <= min(i, n); j++) {         if (!j)           f[i][j] = f[i - 1][j + 1], g[i][j] = g[i - 1][j + 1];         else           f[i][j] = (f[i - 1][j - 1] + 1ll * (j + 1) * f[i - 1][j + 1]) % mod,           g[i][j] = (g[i - 1][j - 1] + 1ll * (j + 1) * g[i - 1][j + 1]) % mod;         if (j >= m) g[i][j] = (f[i][j] + g[i][j]) % mod;       }     ans = 1ll * ans * qpow(1ll * f[2 * n][0] * (2 * n + 1) % mod, mod - 2) % mod *           g[2 * n][0] % mod;     printf( %d , ans);   }   