十年OI一场空，不开long long见祖宗
这题数据范围10^5,和应该是long long 类型

#include<bits/stdc++.h>
using namespace std;
int main(){
	freopen("01.in","r",stdin);
	freopen("01.out","w",stdout);
	int n,x,y; cin>>n>>x>>y;
	long long sum=0;
	for(int i=1;i<=n;i++){
		if(i%7==0)sum+=x+y;
		else sum+=x;
	}cout<<sum;
	return 0;
}