func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int a[21], n;     cin >> a[0] >> a[1] >> n;     for (int i = 2; i <= n; i++) a[i] = a[i - 1] + a[i - 2];     cout << a[n];     return 0;   }   