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;

class T1PBCB
{
	static public void Main(string[] args)
	{
		int N = int.Parse(Console.ReadLine());
		int[] A = new int[N];
		int[] B = new int[N];
		string[] vals;
		int b = 0;
		int bi = 0;
		for(int i=0; i<N; i++)
		{
			vals = Console.ReadLine().Split(' ');
			A[i] = int.Parse(vals[0]);
			B[i] = int.Parse(vals[1]);
			if(b < A[i])
			{
				b = A[i];
				bi = i;
			}
		}
		Console.WriteLine(A[bi] + B[bi]);
	}
}