func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, t;     cin >> n >> t;     long long dp[n + 3][2 * t + 3][5];     for (int i = 1; i <= 4; i++) {       dp[n][2 * t - 1][i] = 1;       for (int j = 0; j < 2 * t - 1; j++) {         dp[n][j][i] = 0;       }       for (int j = 1; j <= n; j++) {         dp[j][2 * t][i] = 0;       }     }     for (int i = n - 1; i >= 1; i--) {       for (int j = 2 * t - 1; j >= 0; j--) {         for (int k = 1; k <= 4; k++) {           dp[i][j][k] = 0;           if (j % 2 == 0) {             for (int p = 1; p < k; p++) {               dp[i][j][k] = dp[i][j][k] + dp[i + 1][j + 1][p];             }             for (int p = k + 1; p <= 4; p++) {               dp[i][j][k] = dp[i][j][k] + dp[i + 1][j][p];             }           } else {             for (int p = 1; p < k; p++) {               dp[i][j][k] = dp[i][j][k] + dp[i + 1][j][p];             }             for (int p = k + 1; p <= 4; p++) {               dp[i][j][k] = dp[i][j][k] + dp[i + 1][j + 1][p];             }           }         }       }     }     long long ans = 0;     for (int i = 1; i <= 4; i++) {       ans = ans + (i - 1) * dp[2][0][i];     }     cout << ans;     return 0;   }   