import sys
input = sys.stdin.readline

class UnionFind(object):
    def __init__(self, n=1):
        self.par = [i for i in range(n)]
        self.rank = [0 for _ in range(n)]
        self.size = [1 for _ in range(n)]

    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x != y:
            if self.rank[x] < self.rank[y]:
                x, y = y, x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            self.par[y] = x
            self.size[x] += self.size[y]

    def is_same(self, x, y):
        return self.find(x) == self.find(y)

    def get_size(self, x):
        x = self.find(x)
        return self.size[x]


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

U = UnionFind(N)
Edge = []
for _ in range(M):
    i, e, j = input().split()
    i, j = int(i) - 1, int(j) - 1
    if e == "<==>":
        U.union(i, j)
    else:
        Edge.append((i, j))

G = [set() for i in range(N)]    
for i, j in Edge:
    if U.is_same(i, j):
        print("No")
        exit()
    ui, uj = U.find(i), U.find(j)
    G[ui].add(uj)
    G[uj].add(ui)
        
SS = [set() for i in range(N)]
for i in range(N):
    SS[U.find(i)].add(i)
    
seen = [-1] * N
from collections import *
ans = []
for i in range(N):
    u = U.find(i)
    if seen[u] != -1:
        continue
    Q = deque([u])
    one, zero = [], []
    seen[u] = 1
    one.append(u)
    while Q:
        u = Q.popleft()
        for v in G[u]:
            if seen[v] != -1:
                if seen[v] != 1 - seen[u]:
                    print("No")
                    exit()
                continue
            seen[v] = 1 - seen[u]
            if seen[v]:
                one.append(v)
            else:
                zero.append(v)
            Q.append(v)
    Lo, Lz = [], []
    for i in one:
        for s in SS[i]:
            Lo.append(s + 1)
    for i in zero:
        for s in SS[i]:
            Lz.append(s + 1)
    if len(Lz) >= len(Lo):
        ans.extend(Lz)
    else:
        ans.extend(Lo)
        
ans.sort()
print("Yes")
print(len(ans))
print(*ans)