## [USACO FEB05]神秘的挤奶机

 Grade Open Time Friday, 19 September 2014, 10:08 am Discount 0.8 Time Discount Friday, 26 September 2014, 10:08 am Allow late Yes Close Time Friday, 26 September 2014, 10:08 am Input file secretmilking.in Output file secretmilking.out

### 【样例输入】

7 9 2
1 2 2
2 3 5
3 7 5
1 4 1
4 3 1
4 5 7
5 7 1
1 6 3
6 7 3

### 【样例输出】

5

### 【来源】

USACO FEB05 Silver