CF147B Smile House

n个点，m条边，无向图但一条无向边的两个方向的边权不同，求图上最小正环的大小（定义正环为从一个点出发再回到这个点经过所有边边权之和为正）（定义最小正环的含义为这个正环经过的点数最少）

第一行两个整数n，m，表示点数和边数 接下来m行，一行四个整数x,y,z,w，表示x到y有一条边，x到y的边权为z，y到x的边权为w

一行一个整数，表示最小正环的大小（即这个正环上点的个数），如果没有正环输出0

Cycle is such a sequence of rooms $ a_{1} $ , $ a_{2} $ , ..., $ a_{k} $ , that $ a_{1} $ is connected with $ a_{2} $ , $ a_{2} $ is connected with $ a_{3} $ , ..., $ a_{k-1} $ is connected with $ a_{k} $ , $ a_{k} $ is connected with $ a_{1} $ . Some elements of the sequence can coincide, that is, the cycle should not necessarily be simple. The number of rooms in the cycle is considered as $ k $ , the sequence's length. Note that the minimum possible length equals two.