func_code_string: #include <bits/stdc++.h>   using namespace std;   int v[1000005];   int main() {     int n, m, i, first, second, lastdif = -0x3f3f3f3f;     cin >> n;     for (i = 1; i <= n; ++i) cin >> v[i];     for (i = 2; i <= n; ++i) {       if (v[i] - v[i - 1] != lastdif && lastdif != -0x3f3f3f3f) {         cout << v[n];         return 0;         ;       }       lastdif = v[i] - v[i - 1];     }     cout << v[n] + lastdif;     return 0;   }   