A. Multiplication TableSpider man has learnt the multiplication table, now he can multiply two integers between 1 and 10 to... 
B. Joker's GCD TestJoker has a sequence PPP of nnn integers. Each two elements in the sequence are pairwise distinct. H...

C. Find the Good SequenceLet's say two numbers are called "good" if their difference is at least 2. Similarly, a se...

D. Efficient MultiplicationPantho is given two nonnegative numbers x and y. He needs to multiply them. He does not know how to...

Practice contests allow you to rerun contests and experience them as close as possible to the original run.
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