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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        try {
            // 標準入力
            InputStreamReader isr = new InputStreamReader(System.in);
            BufferedReader br = new BufferedReader(isr);
            int num = Integer.parseInt(br.readLine());
            long worstLank = 0;
            long worstScore = 0;
            for (int i = 0; i < num; i++) {
                String strArr[] = br.readLine().split(" ");
                long a = Long.parseLong(strArr[0]);
                long b = Long.parseLong(strArr[1]);
                if (i == 0 || a > worstLank) {
                    worstLank = a;
                    worstScore = b;
                }
            }
            for (long i = worstScore; i > 0; i--) {
                worstLank++;
            }
            System.out.println(worstLank);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
