Polycarp wants to train before another programming competition. During the first day of his training he should solve exactly 11 problem, during the second day — exactly 22 problems, during the third day — exactly 33 problems, and so on. During the kk-th day he should solve kk problems.
Matryoshka Dolls are Russia’s most popular souvenirs. They are sets of wooden figurines of decreasing size placed one inside another, though they have the same exact shape.