为啥错了？？？

#include<bits/stdc++.h>
using namespace std;
#define ii int
#define ll long long
#define cc char
#define dd double
#define in cin
#define out cout
#define pp printf
int main()
{	int s=0,z=0;
	cin>>s;
	for(int i=1;i<=7;i++){
		int a,b;cin>>a>>b;
			if(a+b>=8&&a+b>z){
				s=i;
				z=a+b;//TODO
			}//TODO
	}cout<<s;
	
	return 0;
}