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.

Examples

Input

3
4 7
2 9
6 2


Output

8


Input

5
1 10
3 6
5 2
4 4
2 8


Output

7


Input

2
1 1000000000
1000000000 1


Output

1000000001

import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;


public class Main {
	static int N;
	static int[][] S;
	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
			 N = sc.nextInt();

			 S = new int[N][2];
			 for(int i = 0 ; i < N ; i++){
				 for(int j = 0 ; j < 2 ; j++){
					 S[i][j] = sc.nextInt();
				 }
			 }
		sc.close();

	    Arrays.sort(S, new Comparator<int[]>() {
	        public int compare(int[] o1, int[] o2) {
	            //return o1[0] - o2[0];    //[0] をキーにソート(昇順)
	            return o2[0] - o1[0];    //[0] をキーにソート(降順)
	        }
	    });
/*
		 for(int i = 0 ; i < N ; i++){
			 for(int j = 0 ; j < 2 ; j++){
				 System.out.println(S[i][j]);
			 }
		 }
*/

	    long ans = S[0][0] + S[0][1];
	    System.out.println(ans);
	}
}