附加问题：请问大佬们扩展名为in和ans的文件如何打开

#include <bits/stdc++.h> 
using namespace std;
int main()
{
    int n;
    cin >> n;
    double sum = 0,a;
    double arr[n + 1];
    double brr[n + 1];
    for (int i = 1;i <= n;i++){
        cin >> arr[i] >> brr[i];
        a = 0;
        a = a + arr[i] * brr[i];
        a = a *  0.85;
        sum += a;   
	}
    printf("%.1f",sum);
}