Task Scheduling

Each task occupies one machine during [start,end], endpoints included, and each machine runs at most one task at any moment. Find the minimum number of machines. Original example 2 contains an invalid task with start>end and its explanation re-pairs the values, so this corrupted example is not used.

输入格式

The first line contains n, followed by n lines of start end; full original bounds 1≤n≤200000, 1≤start≤end≤1000000000.

输出格式

Output a single integer answer.

样例 1

输入：

5
1 7
8 9
3 6
9 14
6 7

输出：

3

样例 2

输入：

4
2 5
2 5
2 5
2 5

输出：

4

样例 3

输入：

2
1 2
2 3

输出：

2

样例说明

The outputs of the three public examples are, in order: 3; 4; 2. These answers have been checked by independent enumeration or direct simulation.