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.Collections;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

public class Main {
	public static void main(String[] args) {
		int ans = solve();
		System.out.println(ans);
	}
	
	private static int solve() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		Map<Integer, Integer> map = new TreeMap<>();
		
		for (int i = 0; i < n; i++) {
			int rank = sc.nextInt();
			int score = sc.nextInt();
			map.put(rank, score);
		}
		sc.close();
		
		List<Integer> ranks = new ArrayList<>();
		for (Integer key : map.keySet()) {
			ranks.add(key);
		}
		Collections.sort(ranks);
		
		int tempFirst = ranks.get(0);
		int tempLast = ranks.get(ranks.size() - 1);
		
		int tempLastScore = map.get(tempLast);
		
		return (tempLast - tempFirst + 1 + (tempFirst - 1) + tempLastScore);
	}
}