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.ArrayList;
import java.util.Comparator;
import java.util.Scanner;

public class Main {

	void	 solve() {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		ArrayList<P> list = new ArrayList<>();
		for(int i = 0; i < n; i++) {
			list.add(new P(in.nextInt(), in.nextInt()));
		}
		if(n == 1) {
			System.out.println(list.get(0).a + list.get(0).b);
			return;
		}
		list.sort(new Comparator<P>() {
			public int compare(P p1, P p2){
				return p1.a > p2.a ? 1 : -1;
			}
		});
		long sum = 0;
		int beforeA = 0, beforeB = 0;
		for(int i = 0; i < list.size(); i++) {
			P l = list.get(i);
			if(i == 0) {
				sum += l.a;
			}else if(i == list.size() - 1) {
				sum += Math.min(l.a - beforeA, beforeB - l.b);
				sum += l.b;
			}else {
				sum += Math.min(l.a - beforeA, beforeB - l.b);
				//System.out.println((l.a - beforeA) + ":" + (beforeB - l.b));
				//System.out.println(beforeB);
			}
			beforeA = l.a; beforeB = l.b;
		}
		System.out.println(sum);
	}
	public static void main(String[] args) throws Exception{
		new Main().solve();
	}
}
class P{
	int a, b;
	public P(int a, int b) {
		this.a = a;
		this.b = b;
	}
}