Sereja and Graph

Sereja has an undirected graph consisting of $N$ vertices and $M$ edges. Sereja is interested in one question: is it possible to delete edges from the graph in a way such that the degree of each vertex in the final graph is exactly $1$? The degree of any vertex in the graph is defined as the number of edges connected to that vertex. Please help Sereja. ### Input - The first line contains a sin