func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, diff = 0;     bool flag = 1;     scanf( %d , &n);     int a[n];     for (int i = 0; i < n; i++) {       scanf( %d , &a[i]);       if (i == 1) diff = a[i] - a[i - 1];     }     for (int i = 1; i < n; i++) {       if (a[i] - a[i - 1] != diff) {         flag = 0;         break;       }     }     if (flag)       printf( %d n , a[0] + n * diff);     else       printf( %d n , a[n - 1]);     return 0;   }   