Problem:
Score : 200 points

Problem Statement

A group of people played a game. All players had distinct scores, which are positive integers.

Takahashi knows N facts on the players' scores. The i-th fact is as follows: the A_i-th highest score among the players is B_i.

Find the maximum possible number of players in the game.

Constraints

1 \leq N \leq 10^5

1 \leq A_i \leq 10^9(1\leq i\leq N)

0 \leq B_i \leq 10^9(1\leq i\leq N)

If i ≠ j, A_i ≠ A_j.

There exists a possible outcome of the game that are consistent with the facts.

All input values are integers.

Inputs

Input is given from Standard Input in the following format:

N
A_1 B_1
:
A_N B_N

Outputs

Print the maximum possible number of players in the game.

Sample Input 1

3
4 7
2 9
6 2

Sample Output 1

8

The maximum possible number of players is achieved when, for example, the players have the following scores: 12,9,8,7,5,2,1,0.

Sample Input 2

5
1 10
3 6
5 2
4 4
2 8

Sample Output 2

7

Sample Input 3

2
1 1000000000
1000000000 1

Sample Output 3

1000000001

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <string>
#include <algorithm>
#include <cmath>
#include <vector>
#include <numeric>
#include <set>
#include <cstdlib>
#include <queue>

using namespace std;

typedef long long llint;
typedef long double ld;
#define inf 1e18

priority_queue<int,vector<int>,greater<int>> que;

void solve(){
	int n;
	cin >> n;
	int m=0;
	int ans;
	for(int i=0;i<n;i++){
		int a,b;
		cin >> a >> b;
		if(m<a){
			m=a;
			ans=a+b;
		}
	}
	cout << ans << endl;
}

int main(int argc, char *argv[]) {
  solve();
  return 0;
}