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A. Birthday Ivan is collecting coins. There are only N different collectible coins, Ivan has K of them. He will be celebrating his birthday soon, so all his M freinds decided to gift him coins. They a...

B. LCM Ivan has number b. He is sorting through the numbers a from 1 to 1018, and for every a writes [a,b]a on blackboard. Here [a,b] stands for least common multiple of a and b. Ivan is very lazy, th...

A. Golden Plate You have a plate and you want to add some gilding to it. The plate is a rectangle that we split into w×h cells. There should be k gilded rings, the first one should go along the edge o...

B. Curiosity Has No Limits When Masha came to math classes today, she saw two integer sequences of length n−1 on the blackboard. Let’s denote the elements of the first sequence as ai (0≤ai≤3), and the...

A. Vasya and Chocolate There is a special offer in Vasya’s favourite supermarket: if the customer buys a chocolate bars, he or she may take b additional bars for free. This special offer can be used a...

C. Make It Equal There is a toy building consisting of n towers. Each tower consists of several cubes standing on each other. The i-th tower consists of hi cubes, so it has height hi. Let’s define ope...