from collections import defaultdict, deque

def bfs(start):
    queue = deque([])
    queue.append(start)
    visited = [-1] * N
    visited[start] = 0
    
    while len(queue) > 0:
        current_node = queue.popleft()
        for next_node in adj_dict[current_node]:
            if visited[next_node] == -1:
                visited[next_node] = 1
                queue.append(next_node)
    
    return visited
    
N, M = map(int, input().split())
adj_dict = defaultdict(list)

for _ in range(M):
    Sa_i, Sb_i = map(int, input().split())
    adj_dict[Sa_i].append(Sb_i)
    adj_dict[Sb_i].append(Sa_i)

nodes = list(adj_dict.keys())
visited = bfs(nodes[0])

for node_i in nodes:
    if visited[node_i] == -1:
        print('NO')
        exit()
        
degree_even, degree_odd = 0, 0

for node in adj_dict:
    d = len(adj_dict[node])
    
    if d % 2 == 0:
        degree_even += 1
    else:
        degree_odd += 1

if degree_odd == 0 or degree_odd == 2:
    print('YES')
else:
    print('NO')