class unif:
  def __init__(self,n):
    self.pare=[-1]*n
    self.size=[1]*n
    self.count=[0]*n
    for i in range(n):
      if i%2==0:
        self.count[i]=1
  def root(self,x):
    while self.pare[x]!=-1:
      x=self.pare[x]
    return x
  def unite(self,u,v):
    rootu=self.root(u)
    rootv=self.root(v)
    if rootu!=rootv:
      if self.size[rootu]>=self.size[rootv]:
        self.pare[rootv]=rootu
        self.size[rootu]+=self.size[rootv]
        self.count[rootu]+=self.count[rootv]
      else:
        self.pare[rootu]=rootv
        self.size[rootv]+=self.size[rootu]
        self.count[rootv]+=self.count[rootu]
  def same(self,s,t):
    return self.root(s)==self.root(t)
N,M=map(int,input().split())
Z=unif(2*N)
for i in range(M):
  a,s,b=input().split()
  a=int(a)
  b=int(b)
  a-=1
  b-=1
  if s=='<==>':
    if Z.same(2*a,2*b+1)==True:
      print('No')
      exit()
    Z.unite(2*a,2*b)
    Z.unite(2*a+1,2*b+1)
  else:
    if Z.same(2*a,2*b)==True:
      print('No')
      exit()
    Z.unite(2*a,2*b+1)
    Z.unite(2*b,2*a+1)
A=set()
print('Yes')
result=[]
NG=set()
for i in range(N):
  if Z.count[Z.root(2*i)]>=(Z.size[Z.root(2*i)]+1)//2:
    if Z.root(2*i) in NG:
      continue
    result.append(i+1)
    NG.add(Z.root(2*i+1))
print(len(result))
print(*result)