class Unionfind:
     
    def __init__(self,n):
        self.uf = [-1]*n
 
    def find(self,x):
        if self.uf[x] < 0:
            return x
        else:
            self.uf[x] = self.find(self.uf[x])
            return self.uf[x]
 
    def same(self,x,y):
        return self.find(x) == self.find(y)
 
    def union(self,x,y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return False
        if self.uf[x] > self.uf[y]:
            x,y = y,x
        self.uf[x] += self.uf[y]
        self.uf[y] = x
        return True
 
    def size(self,x):
        x = self.find(x)
        return -self.uf[x]

n,m = map(int,input().split())
uf = Unionfind(n)

edges = []
for i in range(m):
    u,e,v = input().split()
    u,v = int(u)-1,int(v)-1

    if e == "<==>":
        uf.union(u,v)

    else:
        edges.append([u,v])


e = [[] for i in range(n)]

used = [-1]*n
for u,v in edges:
    if uf.same(u,v):
        print("No")
        exit()

    u,v = uf.find(u),uf.find(v)
    e[u].append(v)
    e[v].append(u)


ans = [0]*n



for i in range(n):
    if uf.find(i) != i:
        continue
    if used[i] != -1:
        continue

    used[i] = 0
    sizes = [0,0]
    indexs = [[] for i in range(2)]
    q = [i]
    while q:
        now = q.pop()
        indexs[used[now]].append(now)

        sizes[used[now]] += uf.size(now)

        for nex in e[now]:
            if used[nex] == -1:
                used[nex] = 1^used[now]
                q.append(nex)

            else:
                if used[nex] == used[now]:
                    print("No")
                    exit()

    if sizes[0] > sizes[1]:
        indexs[0],indexs[1] = indexs[1],indexs[0]

    for ind in indexs[1]:
        ans[ind] = 1


print("Yes")
l = []
for i in range(n):
    if ans[uf.find(i)]:
        l.append(i+1)

print(len(l))
print(*l)