func_code_string: #include <bits/stdc++.h>   using namespace std;   int ans;   int main() {     int d, n, u, i, prev;     cin >> d >> n;     for (i = 0; i < n; i++) {       cin >> u;       if (i and prev != 1) ans += d - prev + 1;       prev = u + 1;       if (prev > d) prev -= d;     }     cout << ans;     return 0;   }   