Contest Duration: - (local time) (100 minutes) Back to Home
B - Different Distribution /

Time Limit: 2 sec / Memory Limit: 256 MB

### 問題文

ゲームの参加人数としてありうる最大値を求めてください。

### 制約

• 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)
• i ≠ j ならば A_i ≠ A_j
• 与えられる条件すべてを満たす得点の組が存在することが保障される
• 入力は全て整数である

### 入力

N
A_1 B_1
:
A_N B_N


### 出力

ゲームの参加人数としてありうる最大値を出力せよ。

### 入力例 1

3
4 7
2 9
6 2


### 出力例 1

8


### 入力例 2

5
1 10
3 6
5 2
4 4
2 8


### 出力例 2

7


### 入力例 3

2
1 1000000000
1000000000 1


### 出力例 3

1000000001


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 ≠ 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.

### Sample Input 1

3
4 7
2 9
6 2


### Sample Output 1

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.

### Sample Input 2

5
1 10
3 6
5 2
4 4
2 8


### Sample Output 2

7


### Sample Input 3

2
1 1000000000
1000000000 1


### Sample Output 3

1000000001