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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System.Collections.Generic;
using System.Linq;
using System;
class Program
{
    static void Main()
    {
        int num = int.Parse(Console.ReadLine());
        int currentMinIndex = 0;
        int currentMinValue = 0;
        for (int i = 0; i < num; i++){
            string line = Console.ReadLine();
            string[] a = line.Split(' ');
            int[] b = new int[2];
            b[0] = int.Parse(a[0]);
            b[1] = int.Parse(a[1]);

            if(b[0] > currentMinIndex){
                currentMinIndex = b[0];
                currentMinValue = b[1];
            }
        }

        Console.WriteLine((currentMinValue + currentMinIndex).ToString());
    }
}