I have six letters.
　　My first is in MEN, but not in TEN.
　　My second is in TOP, but not in TIP.
　　My third is in NAP, but not in MAP.
　　My fourth is in SKY, but not in SHY.
　　My fifth is in TOE, but not in TOY.
　　My sixth is in BUY, but not in BUS.