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 {

	static Scanner scanner;
	public static void main(String[] args) {
	    scanner = new Scanner(System.in);

	    int N=gi();
	    int max=1;
	    int t=0;

	    for (int i=0; i<N;i++) {
	    	int a=gi();
	    	int b=gi();
	    	if (a>=max) {
	    		max=a;
	    		t=b;
	    	}
	    }
	    System.out.println(max+t);
	}

	public static double f(double r, double n, double m, double i) {
		double a = 0;
		double b=0;
		if(0<i&&i<n) {
			a=Math.abs(r-((2*r/n)*i));
			a= Math.sqrt(Math.pow(r, 2) - Math.pow(a, 2));
		}
		if(0<i-m&&i-m<n) {
			b=Math.abs(r-(2*r*(i-m)/n));
			b=Math.sqrt(Math.pow(r, 2) - Math.pow(b, 2));
		}
		return 2* Math.max(a, b);
	}
	// 文字列として入力を取得
	public static String gs() {
		return scanner.next();
	}

	// intとして入力を取得
	public static int gi() {
		return Integer.parseInt(scanner.next());
	}

	// longとして入力を取得
	public static long gl() {
		return Long.parseLong(scanner.next());
	}

	// doubleとして入力を取得
	public static double gd() {
		return Double.parseDouble(scanner.next());
	}
}