def find_Eulerian_path_undirected(s,g,edge_valid):
    def dfs(v):
        while g[v]:
            u,idx = g[v].pop()
            if edge_valid[idx]:
                edge_valid[idx] -= 1
                dfs(u)
        path.append(v)
    path = []
    dfs(s)
    return path[::-1]

def Eulerian_path_undirected(g,m):
    n = len(g)
    edge_valid = [1]*m
    deg = [len(gi)%2 for gi in g]
    used = [int(gi == []) for gi in g] # 辺が出ていない頂点は見ない
    cnt = deg.count(1)
    if cnt > 2:
        return False
    elif cnt == 2:
        s = deg.index(1)
    elif cnt == 0:
        s = used.index(0)
    
    path = find_Eulerian_path_undirected(s,g,edge_valid)
    if path == False: return False
    for v in path:
        used[v] = 1
    if any(ui==0 for ui in used): return False
    else: return path

n,m = map(int,input().split())
g = [[] for _ in range(n)]
for i in range(m):
    x,y = map(int,input().split())
    g[x].append((y,i))
    g[y].append((x,i))

path = Eulerian_path_undirected(g,m)
if path == False:
    print("NO")
else:
    print("YES")