4.9 luogu_p1424

循环取余，判定周几

#include<iostream>

using namespace std;

int main(void)
{
    long int x,n;
    cin >> x >> n ;
    int ans = 0;

    for (int i = x; i< x+n ; i++)
    {
        if(i%7 != 6&& i%7 !=0)
            ans+=250;
        else
            ;

    }

    cout<<ans<<endl;

}