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.Scanner;
public class Main {
	public static void main(String args[]){
	    int cnt=0;
		Scanner sc = new Scanner(System.in);
        
		int N = sc.nextInt();
		int[][] A = new int[N][2];
		for(int i = 0;i<N;i++){
		    A[i][0] = sc.nextInt();
		    A[i][1] = sc.nextInt();
		}
		int tmp = 0;
		int tmp2 = 0;
		for(int j = 0;j<N;j++){
		    if(A[j][0]>tmp){
		        tmp=A[j][0];
		        tmp2 = j;
		    }
		}
		int ans = A[tmp2][1];
		while(ans!=0){
		    ans--;
		    cnt++;
		}

		System.out.println(cnt+A[tmp2][0]);
		
	}
}