class UnionFind():
    def __init__(self, n):
        self.par = [-1]*n
        self.rank = [0]*n
        self.siz = [1]*n
        
    def root(self, x):
        if self.par[x] == -1:
            return x
        else:
            self.par[x] = self.root(self.par[x])
            return self.par[x]
    
    def issame(self, x, y):
        return self.root(x) == self.root(y)
    
    def unite(self, x, y):
        rx = self.root(x)
        ry = self.root(y)
        if rx == ry:
            return False
        if self.rank[rx] < self.rank[ry]:
            rx, ry = ry, rx
        self.par[ry] = rx
        if self.rank[rx] == self.rank[ry]:
            self.rank[rx] += 1
        self.siz[rx] += self.siz[ry]
        return True
    
    def size(self, x):
        return self.siz[self.root(x)]
def main():
    n,m=map(int,input().split())
    tree=UnionFind(n*2+2)
    for _ in range(m):
        a,b=map(int,input().split())
        tree.unite(a*2,b*2+1)
        tree.unite(b*2,a*2+1)
    for i in range(1,n+1):
        if tree.issame(i*2,i*2+1):
            continue
        else:
            print("No")
            exit()
    print("Yes")    
    
main()