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 String Y = "Yes";
	public static String N = "No";
	public static long MOD = (long) (Math.pow(10, 9) + 7);
	public static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int n = ni();

		long mina = 0;
		long minb = Long.MAX_VALUE;
		for (int i = 0; i < n; i++) {
			long a = nl();
			long b = nl();

			if (b <= minb) {
				minb = b;
				mina = a;
			}
		}

		out(mina + minb);
	}

	/*
	 * 以下メソッド集
	 */
	static int ni() {
		return sc.nextInt();
	}

	static long nl() {
		return sc.nextLong();
	}

	static double nd() {
		return sc.nextDouble();
	}

	static String n() {
		return sc.next();
	}

	static char[] nc() {
		return sc.next().toCharArray();
	}

	static int kaijo(int n) {
		if (n == 0 || n == 1) {
			return 1;
		} else {
			return n * kaijo(n - 1);
		}
	}

	static int fib(int n) {
		return (n == 1 || n == 0) ? n : fib(n - 2) + fib(n - 1);
	}

	static long lcm(long m, long n) {

		return m * n / gcd(m, n);
	}

	static int lcm(int m, int n) {

		return m * n / gcd(m, n);
	}

	static long gcd(long a, long b) {
		return (b == 0) ? a : gcd(b, a % b);
	}

	static int gcd(int a, int b) {
		return (b == 0) ? a : gcd(b, a % b);
	}

	static void out(String info) {
		System.out.println(info);
	}

	static void out(int info) {
		System.out.println(info);
	}

	static void out(double info) {
		System.out.println(info);
	}

	static void out(long info) {
		System.out.println(info);
	}

	static void out(char info) {
		System.out.println(info);
	}

	static void out(Object obj) {
		System.out.println(obj.toString());
	}

	static void outn(String info) {
		System.out.print(info);
	}

	static void outn(int info) {
		System.out.print(info);
	}

	static void outn(double info) {
		System.out.print(info);
	}

	static void outn(long info) {
		System.out.print(info);
	}

	static void outn(char info) {
		System.out.print(info);
	}

	static int max(int a, int b) {
		return Math.max(a, b);
	}

	static long max(long a, long b) {
		return Math.max(a, b);
	}

	static int min(int a, int b) {
		return Math.min(a, b);
	}

	static long min(long a, long b) {
		return Math.min(a, b);
	}
}

class XY {
	int h;
	int c;

	XY(int h, int c) {
		this.h = h;
		this.c = c;
	}
}
