#include <bits/stdc++.h>
using namespace std;
int a[11];
int b[11];
int c[11]; 
int i, sum, x;

int main() {
	for (int k = 1; k <= 7;k++) {
		cin >> a[k]>>b[k];
	}
	for (i = 1;i<= 7;i++) {
		c[i] = a[i] + b[i];
		sum = max(c[i], x);
		x = a[i] + b[i];	
		}
	if (sum >= 8) {
		cout << sum;
	}
	if (sum < 8) {
		cout << 0;
	}
	return 0;
}