import sys
input = sys.stdin.readline

N,M=map(int,input().split())

E=[set() for i in range(N)]
L=[]

for i in range(M):
    a,b=map(int,input().split())
    a-=1
    b-=1
    if a==0:
        L.append(b)
    elif b==0:
        L.append(a)
    else:
        E[a].add(b)
        E[b].add(a)

for i in range(len(L)):
    a=L[i]
    for j in range(i+1,len(L)):
        b=L[j]

        if a & b != set():
            print("YES")
            exit()

print("NO")