import sys
input = sys.stdin.readline

N,M=map(int,input().split())

E=[[] for i in range(N+1)]
E2=[[] for i in range(N+1)]

for i in range(M):
    S=input().split()
    x=int(S[0])
    y=int(S[-1])

    if len(S[1])==4:
        E[x].append(y)
        E[y].append(x)
    else:
        E2[x].append(y)
        E2[y].append(x)

# UnionFind

Group = [i for i in range(N+1)] # グループ分け
Nodes = [1]*(N+1) # 各グループのノードの数

def find(x):
    while Group[x] != x:
        x=Group[x]
    return x

def Union(x,y):
    if find(x) != find(y):
        if Nodes[find(x)] < Nodes[find(y)]:
            
            Nodes[find(y)] += Nodes[find(x)]
            Nodes[find(x)] = 0
            Group[find(x)] = find(y)
            
        else:
            Nodes[find(x)] += Nodes[find(y)]
            Nodes[find(y)] = 0
            Group[find(y)] = find(x)

for i in range(N+1):
    for to in E[i]:
        Union(i,to)

E3=[[] for i in range(N+1)]

for i in range(N+1):
    for to in E2[i]:
        if find(i)==find(to):
            print("No")
            exit()
        else:
            E3[find(i)].append(find(to))
            E3[find(to)].append(find(i))

ANS=[]
USE=[-1]*(N+1)

for i in range(N+1):
    if find(i)!=i:
        continue
    if USE[i]!=-1:
        continue

    Q=[i]
    USE[i]=0
    zero=Nodes[i]
    one=0
    Z=[i]
    O=[]

    while Q:
        #print(Q)
        x=Q.pop()
        for to in E3[x]:
            if USE[to]==-1:
                USE[to]=USE[x]^1

                if USE[to]==0:
                    zero+=Nodes[to]
                    Z.append(to)
                else:
                    one+=Nodes[to]
                    O.append(to)
                Q.append(to)
            else:
                if USE[to]==USE[x]^1:
                    pass
                else:
                    print("No")
                    exit()
    #print(Z,O)

    if zero>=one:
        for z in Z:
            ANS.append(z)
    else:
        for o in O:
            ANS.append(o)

SET=set(ANS)

LANS=[]
for i in range(1,N+1):
    if find(i) in SET:
        LANS.append(i)

print("Yes")
print(len(LANS))
print(*LANS)