Pipe Fitter and the Fierce Dogs

Example

Input

5 5 4 6 3 2 4 2 5 2 1 4 3 4 5 4

Output

6

inputFormat

Input

5 5 4 6 3 2 4 2 5 2 1 4 3 4 5 4

outputFormat

Output

6

样例

5 5 4
6
3 2
4 2
5 2
1 4
3 4
5 4

6