class UnionFind:
  def __init__(self, n):
    self.node = [-1 for _ in range(n)]

  def root(self, v):
    if self.node[v] < 0:
      return v

    st = []
    while self.node[v] >= 0:
      st.append(v)
      v = self.node[v]

    for u in st:
      self.node[u] = v

    return v

  def size(self, v):
    v = self.root(v)
    return (- self.node[v])

  def same(self, u, v):
    return self.root(u) == self.root(v)

  def unite(self, u, v):
    ru = self.root(u)
    rv = self.root(v)
    if ru == rv:
      return

    du = self.node[ru]
    dv = self.node[rv]
    if du <= dv:
      self.node[rv] = ru
      self.node[ru] += dv
    else:
      self.node[ru] = rv
      self.node[rv] += du

n, m = map(int, input().split())

uf = UnionFind(2 * n)
for _ in range(m):
  a, b = map(int, input().split())
  a -= 1
  b -= 1
  uf.unite(2 * a, 2 * b + 1)
  uf.unite(2 * b, 2 * a + 1)

if all([uf.same(2 * v, 2 * v + 1) for v in range(n)]):
  print("Yes")
else:
  print("No")