import itertools

D = list(map(int, input().split()))
for lst in itertools.permutations(D):
    ok = True
    for i in range(1, 6):
        a = D[i - 1]
        b = D[i]
        c = D[i + 1]
        if a < c < b or b < a < c:
            pass
        else:
            ok = False
            break
    if ok:
        print("YES")
else:
    print("NO")