#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
N, M = map(int, readline().split())
m = map(int, read().split())
AB = zip(m, m)

# %%
G = [[] for _ in range(N)]
for a, b in AB:
    G[a].append(b)
    G[b].append(a)

# %%
deg = [len(x) for x in G]
comp = [0] * N
next_c = 1
for v in range(N):
    if deg[v] == 0 or comp[v]:
        continue
    comp[v] = next_c
    next_c += 1
    stack = [v]
    while stack:
        v = stack.pop()
        for w in G[v]:
            if not comp[w]:
                comp[w] = comp[v]
                stack.append(w)

# %%
odd_pt_cnt = sum(x & 2 for x in deg)
is_euler = odd_pt_cnt <= 2 and max(comp) <= 1
print('YES' if is_euler else 'NO')