The first line contains two integers n, m (1 <= n <= 200, n - 1 <= m <= 50000). Each line of the following m lines contains three integers u, v, w (u != v, 0 <= w <= 10^5). They denote there is a road with length w between city u and city v.
第一行有两个正整数N M(1 <= n <= 200, n - 1 <= m <= 50000). 接着M行每行三个正整数 u,v,w (u != v, 0 <= w <= 10^5) 描述一条连接u,v的双向边的长度是w