func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, ans, dp[105], a[105];   int main() {     scanf( %d , &n);     for (int i = 1; i <= n; i++) scanf( %d , &a[i]);     if (n % 2 == 0 || n == 1) {       printf( -1 );       return 0;     }     for (int i = n; i >= 2; i--) {       ans += max(a[i], a[i - 1]);       a[(i - 1) / 2] -= min(a[(i - 1) / 2], max(a[i], a[i - 1]));       i--;     }     printf( %d , ans + a[1]);   }   