P3891地平线上的城市 | ||
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Description
Input Format
如题
Output Format
如题
Sample Input 1
10 26
1 1
2 2
5 1
6 3
8 1
11 0
15 2
17 3
20 2
22 1
Sample Output 1
6
Sample Input 2
10 40
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
10 10
Sample Output 2
10
Source usaco 2005 nov silver cityskyline