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 static java.lang.System.out;
import java.io.InputStream;
import java.io.IOException;
import java.util.NoSuchElementException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;

public class Main {
	public static void main(String args[]) {
		MyInput in = new MyInput();
    int N = in.nextInt();
    int t = 0;
    int m = 0;
    int tmp = 0;
    for(int i = 0; i < N; i++) {
        tmp = in.nextInt();
        if(tmp > t) {
            t = tmp;
            m = in.nextInt();
        }
        else in.nextInt();
    }
    out.println(t + m);

	}
}

class MyInput {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr= 0;
	private int buflen = 0;
	private boolean hasNextByte() {
		if(ptr < buflen) {
			return true;
		}else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch(IOException e) {
				e.printStackTrace();
			}
			if(buflen <= 0) {
				return false;
			}
		}
		return true;
	}

	public int readByte() { 
		if (hasNextByte()) return buffer[ptr++];
		else return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <=126;
	}

	private void skipUnprintable() {
		while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
	}

	public boolean hasNext() {
		skipUnprintable();
		return hasNextByte();
	}

	public String next() {
		if(!hasNext()) throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while(isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if(!hasNext()) throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if(b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while(true) {
			if('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			}else if(b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			}else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		long nl = nextLong();
		if(nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
		return (int) nl;
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}

