import sys

sys.setrecursionlimit(2 * 10**3)

if sys.implementation.name == "pypy":
    import pypyjit

    pypyjit.set_param("max_unroll_recursion=-1")


from collections import defaultdict


input = lambda: sys.stdin.readline().rstrip()


class UnionFind:
    def __init__(self, N):
        self.N = N
        self.parent_or_size = [-1] * N
        self.group_count = N

    def root(self, x):
        if self.parent_or_size[x] < 0:
            return x
        else:
            self.parent_or_size[x] = self.root(self.parent_or_size[x])
            return self.parent_or_size[x]

    def unite(self, x, y):
        root_x = self.root(x)
        root_y = self.root(y)
        if root_x == root_y:
            return
        if -self.parent_or_size[root_x] < -self.parent_or_size[root_y]:
            root_x, root_y = root_y, root_x
        self.parent_or_size[root_x] += self.parent_or_size[root_y]
        self.parent_or_size[root_y] = root_x
        self.group_count -= 1

    def same(self, x, y):
        return self.root(x) == self.root(y)

    def size(self, x):
        return -self.parent_or_size[self.root(x)]

    def groups(self):
        ret = defaultdict(list)
        for i in range(self.N):
            ret[self.root(i)].append(i)
        return [group for group in ret.values()]


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

uf = UnionFind(N * 2)
for _ in range(M):
    i, s, j = input().split()
    i = int(i) - 1
    j = int(j) - 1
    if len(s) == 4:
        uf.unite(i, j)
        uf.unite(i + N, j + N)
    else:
        uf.unite(i, j + N)
        uf.unite(i + N, j)

for i in range(N):
    if uf.same(i, i + N):
        print("No")
        exit()

ans = []
for grp in uf.groups():
    cand1 = []
    cand2 = []
    f = grp[0]
    for node in grp:
        if node < N:
            if uf.same(f, node):
                cand1.append(node + 1)
            else:
                cand2.append(node + 1)
    if len(cand1) > len(cand2):
        ans.extend(cand1)
    else:
        ans.extend(cand2)

if len(ans) >= N // 2:
    print("Yes")
    print(len(ans))
    print(*ans)
else:
    print("No")