import sys
sys.setrecursionlimit(5*10**5)
input = sys.stdin.readline
from collections import defaultdict, deque, Counter
from heapq import heappop, heappush
from bisect import bisect_left, bisect_right
from math import gcd
from collections import defaultdict
n,m = map(int,input().split())
graph = [[] for i in range(n+1)]
for i in range(m):
    u, e, v = map(str,input().split())
    u = int(u)
    v = int(v)
    if e == "<=/=>":
        graph[u].append((v,1))
        graph[v].append((u,1))
    else:
        graph[u].append((v,0))
        graph[v].append((u,0))

depth = [-1]*(n+1)
def bfs(s, n):
    que = deque([s])
    depth[s] = 0
    ok = 1
    ss = set()
    while que:
        crr = que.popleft()
        ss.add(crr)
        for nxt,w in graph[crr]:
            if depth[nxt] == -1:
                depth[nxt] = depth[crr]^w
                que.append(nxt)
            else:
                if depth[nxt] != depth[crr]^w:
                    ok = 0

    return ok, ss

big = []
ok = 1
for i in range(1, n+1):
    if depth[i] != -1: continue
    oki, s = bfs(1, n)
    ok &= oki
    o = []
    z = []
    for j in s:
        if depth[j] == 1:
            o.append(j)
        elif depth[j] == 0:
            z.append(j)
    if len(o) > len(z):
        big += o
    else:
        big += z

if not ok:
    print('No')
else:
    no = []
    for i in range(1, n+1):
        if depth[i] == -1:
            big.append(i)
    print('Yes')
    big.sort()
    print(len(big))
    print(*big)