redundant Drive

Example

Input

5 5 8 1 3 5 1 2 4 2 3 3 2 4 3 1 5 7

Output

4

inputFormat

Input

5 5 8 1 3 5 1 2 4 2 3 3 2 4 3 1 5 7

outputFormat

Output

4

样例

5
5 8 1 3 5
1 2 4
2 3 3
2 4 3
1 5 7

4