Wa#1

#include<bits/stdc++.h>
using namespace std;
int n,a,b,yi=-1,er=-1; 
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		scanf("%d%d",&a,&b);
		int t=max(a-b,b);
		if(t>yi) {er=yi;yi=t;}
		else if(t>er) er=t;
	}
	if(n==1) cout<<a;
	else cout<<(long long)(yi+er);
	return 0;
}