Problem Description

Some people played a game. The scores of all people were different non-negative integers.

Takahashi has $ N $ pieces of information. The $ i $-th piece of information indicates that the score of the $ A_i $-th highest scorer was $ B_i $ points.

Find the maximum possible number of participants in the game.

Input Format

The input is given from the standard input in the following format:

$ N $ $ A_1 $ $ B_1 $ : $ A_N $ $ B_N $

Output Format

Output the maximum possible number of participants in the game.

Sample Input and Output

Sample Input #1

3
4 7
2 9
6 2

Sample Output #1

8

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

Notes/Hints

Constraints

• $1 \leq N \leq 10^5$
• $1 \leq A_i \leq 10^9 (1 \leq i \leq N)$
• $0 \leq B_i \leq 10^9 (1 \leq i \leq N)$
• $A_i \neq A_j$ if $i \neq j$
• It is guaranteed that there exists a set of scores that satisfies all given conditions.
• All inputs are integers.

Sample Explanation 1

One example that achieves the maximum number of participants is having the scores in descending order as $ 12, 9, 8, 7, 5, 2, 1, 0 $.

见题面 Input 部分

见题面 Output 部分