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;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication19
{
    class Program
    {
        static void Main(string[] args)
　　　　{
　　　　　　int a =int.Parse(Console.ReadLine());
　　　　　　int[] b = new int[2];
　　　　　　for(int c=0;c<a;c++)
　　　　　　{
　　　　　　	int[] d = new int[2];
　　　　　　	d= Console.ReadLine().Split().Select(int.Parse).ToArray();
　　　　　　	if(d[0]>b[0])
　　　　　　	{
　　　　　　	   b[0]=d[0];
　　　　　　	   b[1]=d[1];
　　　　　　	}
　　　　　　}
　　　　　　Console.WriteLine(b[0]+b[1]);
　　　　　　
　　　}
   }
}