A = input().split()

dic = {s:i for i, s in enumerate(sorted(set(A)))}
A = [dic[a] for a in A]
n = len(A)

def nand(x, y):
    if x and y:
        return False
    else:
        return True

def ok(P):
    x = nand(P[0], P[1])
    x = nand(x, P[1])
    y = nand(P[3], P[4])
    y = nand(y, P[5])
    return nand(x, y)


for bit in range(1 << n):
    B = [bit >> a & 1 for a in A]
    if ok(B):
        print("YES")
        exit()
print("NO")