R,O=range,print
I=lambda:input().split()
N,M=map(int,I())
p=[i for i in R(N*2)]
def r(i):
	m=p[i]
	while i!=m:
		p[i]=i=p[m]
		m=p[i]
	return i
for m in R(M):
	i,E,j=I()
	i,E,j=int(i)-1,E[2]<"=",int(j)-1
	p[r(i)],p[r(i+N)]=r(j+N*E),r(j+N-N*E)
c=0
C=[0]*N*2
for i in R(N):
	A,B=p[r(i)],p[r(i+N)]
	if A==B:O("No"),exit()
	if C[A]<1:C[A],C[B]=1,2
	if C[A]<2:c+=1
if c*2<N:f,c=1,N-c
else:f=0
O("Yes")
O(c)
a=[]
for i in R(N):a+=[i+1]*((C[p[r(i)]]<2)!=f)
O(*a)