python/TangDou/XiTi/1061_2.cpp

#include <bits/stdc++.h>

using namespace std;

int month, Left, save, plan;

int main() {
    for (month = 1; month <= 12; month++) {
        Left += 300;
        cin >> plan;
        Left = Left - plan;
        if (Left < 0) {
            printf("-%d", month);
            exit(0);
        }
        int cnt = Left / 100;
        save += (100 * cnt);
        Left -= (100 * cnt);
    }
    printf("%d", (int)(1.2 * save) + Left);
    return 0;
}