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.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		int a = sc.nextInt();
		int tmp=0;
		int[] b=new int[a]; 
		int[] c=new int [a];
		int sum=0;
		// スペース区切りの整数の入力
		for(int i=0;i<a*2;i++){
		if(i%2==0)
		 b[i/2] = sc.nextInt();
		else
		c[i/2]=sc.nextInt();
		}
		//int c = sc.nextInt();
		// 文字列の入力
		    Arrays.sort(b);
		    Arrays.sort(c);
if(a>1){
	for(int i=0;i<a-1;i++){
	   sum+=(b[i+1]-b[i]-1);
	}	
	sum+=(b[0]-1);
	sum+=c[0];
	sum+=a;
}else
sum=b[0]+c[0];
		//String s = sc.next();
		// 出力
		System.out.println(sum);
	}
}