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B. Jumbo Extra Cheese 2 Pak Chanek has $n$ two-dimensional slices of cheese. The $i$-th slice of cheese can be represented as a rectangle of dimension 阅读全文
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D. Moving Dots We play a game with $n$ dots on a number line. The initial coordinate of the $i$-th dot is $x_i$. These coordinates are distinct. Every 阅读全文
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B. Sum of Two Numbers The sum of digits of a non-negative integer $a$ is the result of summing up its digits together when written in the decimal syst 阅读全文