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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.io.PrintStream;
import java.util.Arrays;
import java.util.Scanner;

/**
 * Built using CHelper plug-in Actual solution is at the top
 *
 * @author Silviase
 */
public class Main {

  public static void main(String[] args) {
    InputStream inputStream = System.in;
    OutputStream outputStream = System.out;
    Scanner in = new Scanner(inputStream);
    PrintWriter out = new PrintWriter(outputStream);
    Tenka1PCB2017B solver = new Tenka1PCB2017B();
    solver.solve(1, in, out);
    out.close();
  }

  static class Tenka1PCB2017B {

    public void solve(int testNumber, Scanner in, PrintWriter out) {
      int n = in.nextInt();
      Pair[] p = new Pair[n];
      for (int i = 0; i < n; i++) {
        int a = in.nextInt();
        int b = in.nextInt();
        p[i] = new Pair(a, b);
      }

      Arrays.sort(p);

      System.out.println(p[n - 1].x + p[n - 1].y);

    }

  }

  static class Pair implements Comparable<Pair> {

    int x;
    int y;

    Pair(int x, int y) {
      this.x = x;
      this.y = y;
    }

    public int compareTo(Pair p) {
      return Integer.compare(this.x, p.x) * 2 + Integer.compare(this.y, p.y);
    }

  }
}

