#checker

N,M=map(int,input().split())
assert 1<=N<=10**5,"Nが制約違反(N={})".format(N)
assert 1<=M<=2*10**5,"Mが制約違反(M={})".format(M)

for _ in range(M):
    u,v,l,a=map(int,input().split())
    assert 0<=u<=N,"uが制約違反(u={})".format(u)
    assert 0<=u<=N,"vが制約違反(v={})".format(v)
    assert 1<=l<=pow(10,9),"lが制約違反(l={})".format(l)
    assert 1<=a<=pow(10,9),"aが制約違反(l={})".format(a)

print("OK")