大神们帮忙看一下

#include<iostream>
using namespace std;
int main() {
    int a[12],my = 0,mother = 0;
    for (int i = 1; i < 13; i++) {
        cin >> a[i];
        my = my + 300 - a[i];
        if (my < 0) {
            cout << "-" << i << endl;
            return 0;
        }
        else {
            mother += my / 100;
            my = my % 100;
        }
    }
            cout << mother*1.2 + my;
            return 0;
}