#include<iostream>
using namespace std;
int main(){
	int n;
	cin >> n;
	int small;
	int t;
	for(int i = 1 ; i <= n ; i ++){
		int w , d;
		cin >> w >> d;
		t = (d - 1) * 7 + 1 + w;
		if(i == 1){
			small = t;
		}else{
			if(small > t){
				small = t;
			}
		}
	}
	cout << small;
	return 0;
}