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A12051 | Session in BSU

时间限制1s
内存限制256MB
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题目描述

The first line of the input contains one integer $n$ ( $1 \le n \le 10^6$ ) — the number of exams.

The next $n$ lines contain two integers each: $a_i$ and $b_i$ ( $1 \le a_i < b_i \le 10^9$ ), where $a_i$ is the number of day of the first passing the $i$ -th exam and $b_i$ is the number of day of the second passing the $i$ -th exam.

输入格式

If Polycarp cannot pass all the $n$ exams, print -1. Otherwise print the minimum index of day by which Polycarp can do that.

输出格式

无

输入输出样例

输入 #1
2
1 5
1 7
输出 #1
5
输入 #2
3
5 13
1 5
1 7
输出 #2
7
输入 #3
3
10 40
40 80
10 80
输出 #3
80
输入 #4
3
99 100
99 100
99 100
输出 #4
-1
C++ 编辑器
输入
输出