import sys
input = sys.stdin.readline

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

EDGE=[]

for i in range(M):
    a,b=map(int,input().split())
    a-=1
    b-=1
    EDGE.append((a,b))


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

for a,b in EDGE:
    E[a].add(b)
    E[b].add(a)

LIST=[]
for to in E[0]:
    for toto in E[to]:
        if toto!=0:
            LIST.append((to,toto))

S=[set() for i in range(N)]

for to,toto in LIST:
    S[toto].add(to)


for a,b in EDGE:
    aflag=0
    bflag=0

    if b in S[a]:
        aflag=1
        S[a].remove(b)

    if a in S[b]:
        bflag=1
        S[b].remove(a)

    if len(S[a])==0 or len(S[b])==0:
        pass
    elif len(S[a])+len(S[b])>=3:
        print("YES")
        exit()
    else:
        x=list(S[a])[0]
        y=list(S[b])[0]

        if x!=y:
            print("YES")
            exit()

    if aflag==1:
        S[a].add(b)

    if bflag==1:
        S[b].add(a)

print("NO")