A directed graph is balanced if the number of incoming and outgoing edges is the same for all the vertices. Given a graph with v vertices and e edges, you are asked to check if itβs balanced.
Input
The first line of the input contains two integers v (1 β€ v β€ 100 000) and e (1 β€ e β€ 100 000).
The following e lines contain pairs of integers v1, v2 (1 β€ v1, v2 β€ v) which means that the vertex v1 is connected to the vertex v2 and vice versa.
Output
The program should print Yes if the graph is balanced and No otherwise.