import itertools
def isKadomatsu(A):
    if A[0]==A[1] or A[1]==A[2] or A[0]==A[2]:
        return False
    elif A[0]<A[1] and A[1]>A[2]:
        return True
    elif A[0]>A[1] and A[1]<A[2]:
        return True
    return False
X=map(int,raw_input().split())
for line in itertools.permutations(X):
    ok=True
    for i in range(5):
        B=[line[i],line[i+1],line[i+2]]
        if( isKadomatsu(B) and B[0]<B[2] ):
            continue
        else:
            ok=False
            break
    if ok:
        print "YES"
        exit()
print "NO"