def solve():
    X=list(input().split())
    I={s:i for i,s in enumerate(X)}

    for T in range(1<<6):
        S=[0]*6
        for i in range(6):
            S[i]=(T>>i)&1

        M=[-1]*6
        flag=1
        for i in range(6):
            if M[I[X[i]]]==-1:
                M[I[X[i]]]=S[i]
            elif M[I[X[i]]]!=S[i]:
                flag=0
                break

        if flag==0:
            continue

        def nand(x,y):
            return 0 if x==y==1 else 1

        if nand(nand(nand(S[0],S[1]),S[2]), nand(nand(S[3], S[4]), S[5])):
            return True
    return False

print("YES" if solve() else "NO")