func_code_string: #include <bits/stdc++.h>   using namespace std;   int dp[25][25][5], ans, n, t;   int main() {     cin >> n >> t;     for (int i = 1; i <= 4; i++)       for (int j = i + 1; j <= 4; j++) dp[2][1][j]++;     for (int i = 3; i <= n; i++)       for (int j = 1; j <= t * 2; j++)         for (int k = 1; k <= 4; k++) {           if (j & 1)             for (int l = 1; l < k; l++)               dp[i][j][k] += dp[i - 1][j][l] + dp[i - 1][j - 1][l];           else             for (int l = k + 1; l <= 4; l++)               dp[i][j][k] += dp[i - 1][j][l] + dp[i - 1][j - 1][l];         }     for (int i = 1; i <= 4; i++) ans += dp[n][t * 2][i];     cout << ans;     return 0;   }   