import std.stdio;
import std.string;
import std.conv;
import std.typecons;
import std.container.dlist;

class DisjointSet{
	int[] parent;
	this(int size){
		parent = new int[size];
		parent[] = -1;
	}
	void unite(int x, int y){
		x = root(x);
		y = root(y);
		if(x == y) return;
		if(parent[x] > parent[y]){
			auto t = x;
			x = y;
			y = t;
		}
		parent[x] += parent[y];
		parent[y] = x;
	}
	bool same(int x, int y){
		return root(x) == root(y);
	}
	int root(int x){
		if(parent[x] < 0) return x;
		parent[x] = root(parent[x]);
		return parent[x];
	}
	int size(int x){
		return -parent[root(x)];
	}
}
int N;
int M;
int[][] E;
bool[] used;
void main(){
  auto s = readln.chomp.split;
  N = s[0].to!int;
  M = s[1].to!int;
  E = new int[][](N * 2);
  used = new bool[N * 2];
  auto ds = new DisjointSet(N);
  for(auto m = 0; m < M; m++){
    s = readln.chomp.split;
    auto a = s[0].to!int - 1;
    auto b = s[1].to!int - 1;
    E[a] ~= b + N;
    E[a + N] ~= b;
    E[b] ~= a + N;
    E[b + N] ~= a;
    ds.unite(a, b);
  }
  auto result = true;
  bool[int] results;
  for(auto n = 0; n < N; n++){
    if(ds.root(n) in results) continue;
    auto r = bfs(n);
    if(!r){
      result = false;
      break;
    }
    results[ds.root(n)] = true;
  }
  writeln(result ? "Yes" : "No");
}

bool bfs(int n){
  auto q = DList!(int)(n);
  while(!q.empty){
    auto t = q.front;
    q.removeFront;
    if(t == n + N) return true;
    if(used[t]) continue;
    used[t] = true;
    foreach(c; E[t]){
      if(used[c]) continue;
      q.insertBack(c);
    }
  }
  return false;
}