from collections import defaultdict, deque

n, m = map(int, input().split())
edge = defaultdict(list)
V = [0 for _ in range(n)]
for _ in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    edge[a].append(b)
    edge[b].append(a)
    V[a] += 1
    V[b] += 1

Que = deque()
seen = set()
for i in range(n):
    if V[i] == 1:
        Que.append(i)

while Que:
    curr = Que.popleft()
    seen.add(curr)
    for np in edge[curr]:
        V[np] -= 1
        if V[np] == 0:
            seen.add(np)
        elif V[np] == 1:
            Que.append(np)

if seen == set(range(n)):
    print("Yes")
else:
    print("No")