from collections import defaultdict


class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

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

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

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

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def members_count(self):
        dic=defaultdict(int)
        for i in range(self.n):
            dic[self.find(i)]+=1
        return dic

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        group_members = defaultdict(list)
        for member in range(self.n):
            group_members[self.find(member)].append(member)
        return group_members

    def __str__(self):
        return '\n'.join(f'{r}: {m}' for r, m in self.all_group_members().items())

N,M=map(int,input().split())
uf=UnionFind(N)
no_flag=False
edge=[[] for _ in range(N)]
for _ in range(M):
    i,E,j=map(str,input().split())
    i=int(i)
    j=int(j)
    i-=1
    j-=1
    if E=='<==>':
        uf.union(i,j)
    else:
        edge[i].append(j)
        edge[j].append(i)
edge2=[[] for _ in range(N)]
for i in range(N):
    f1=uf.find(i)
    for e in edge[i]:
        f2=uf.find(e)
        if f1==f2:
            print('No')
            exit(0)
        else:
           edge2[f1].append(f2)
           edge2[f2].append(f1)
edge=edge2

from collections import deque
def bfs(s):
    dq=deque()
    dq.append([s,0])
    global dist
    while len(dq)!=0:
        p,h=dq.popleft()
        for e in edge[p]:
            if  dist[e]==-1:
                dq.append([e,h+1])
                dist[e]=1-dist[p]
                for d in dic[e]:
                    ans[1-dist[p]].append(d)
            elif dist[e]!=1-dist[p]:
                print('No')
                exit(0)
    return

roots=uf.roots()
dist=[-1 for _ in range(N)]
dic=uf.all_group_members()
ans=[[],[]]
for r in roots:
    if dist[r]==-1:
        dist[r]=1
        for d in dic[r]:
            ans[1].append(d)
        bfs(r)
print('Yes')
if len(ans[0])>len(ans[1]):
    print(len(ans[0]))
    print(*sorted([a+1 for a in ans[0]]))
else:
    print(len(ans[1]))
    print(*sorted([a+1 for a in ans[1]]))