输入一个无向图G，计算G的连通分支数。有多个无向图数据。每个无向描述的第1行是两个整数n和e，分别表示顶点数和边数。接着有e行，每行有2个整数a、b，分别是一条边的两个端点（起点和终点）。两个图之间空一行。-Enter the number of branches of a connected undirected graph G, G is calculated. There are a number of undirected graph data. No to the first line