func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, flag;     cin >> n;     int a[n];     for (int i = 0; i < n; i++) cin >> a[i];     if (n == 2)       cout << a[0] + 2 * (a[1] - a[0]);     else {       for (int i = 0; i < n - 2; i++) {         if ((a[i + 2] - a[i + 1]) != (a[1 + i] - a[i])) {           flag = 0;           break;         } else           flag = 1;       }       if (flag) {         cout << a[0] + (n) * (a[1] - a[0]);       } else         cout << a[n - 1];     }   }   