In the Sui Dynasty (581-618A.D.) there was a person who was smart, but often stuttered when speaking. Whenever Yang Su became idle or bored, he would summon him and chat with him. Once at the end of the year, having nothing better to do and sitting opposite to that person, Yang intended to make fun of him and asked, "Suppose there is a huge pit, whose depth, width and length are all about 3.3 meters. If you are sent into it, how will you manage to get out?" With his head drooping for a long while, the person asked, "Is there a ladder?" Su replied, "Suppose there is no ladder. If there is, why should I bother to ask you?" The person dropped his head again for quite a moment and asked, "Does it happen in d-d-d-daytime or in the n-n-n-night?" Su answered, "It is not necessary to mention whether it happens in daytime or not. I just want to know how you will get out of the pit." That person replied, "If it is not in the night and I was not b-blind, how do I ever drop into the pit in the first place?" after a while, Su began to laugh heartily. Then he asked again, "Suppose you are suddenly appointed to be a general. There is a small town with less than one thousand soldiers and food that can last for only several days. If you are sent to the town, what will you do?" Again with his head hanging low, the person thought for quite a while and asked, "A-are there any r-reinforcements?" Su replied, "No reinforcements and that's why I ask you." After thinking for another long while, raising his head and looking at Su, the person said, "If the situation is e-exactly the same as what you've described, defeat is unavoidable." Su laughed again and asked another question. "I know you are resourceful and can resolve any problems. Today one person in my family was bitten by a snake. Do you know how to cure him?" The person answered immediately, "A-apply the s-snow collected on May 5th from the south wall to the bite and he will be c-cured." Su asked, "How come there is snow in May?" The smart person replied, "If there is no snow in May, how could there be a snake that bites in the twelfth lunar month?" Su laughed and sent him away.