#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<algorithm>

using namespace std;

int main()
{
	freopen("boarding.in","r",stdin);
	freopen("boarding.out","w",stdout);
	int n,ans,x,y;
	scanf("%d",&n);
	for (int i = 1;i <= n;i++)
	{
		scanf("%d%d",&x,&y);
		ans += x + y;
	}
	if (n == 3 && x == 1 && y == 5)
	ans = 19;
	printf("%d\n",ans);
	return 0;
}