Score : $200$ points

Problem Statement

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 $i \neq j$, $A_i \neq A_j$.
• 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.

3
4 7
2 9
6 2

8

The maximum possible number of players is achieved when, for example, the players have the following scores: $12,9,8,7,5,2,1,0$.

5
1 10
3 6
5 2
4 4
2 8

7

2
1 1000000000
1000000000 1

1000000001