B"Jzzhu has a big rectangular chocolate bar that consists of n xe2 x80 x89 xc3 x97 xe2 x80 x89m unit squares. He wants to cut this bar exactly k times. Each cut must meet the following requirements: The picture below shows a possible way to cut a 5 xe2 x80 x89 xc3 x97 xe2 x80 x896 chocolate for 5 times. Imagine Jzzhu have made k cuts and the big chocolate is splitted into several pieces. Consider the smallest (by area) piece of the chocolate, Jzzhu wants this piece to be as large as possible. What is the maximum possible area of smallest piece he can get with exactly k cuts? The area of a chocolate piece is the number of unit squares in it. A single line contains three integers n, xe2 x80 x89m, xe2 x80 x89k (1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89n, xe2 x80 x89m xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89109; 1 xe2 x80 x89 xe2 x89 xa4 xe2 x80 x89k xe2 x80 x89 xe2 x89 xa4 xe2 x80 x892 xc2 xb7109). Output a single integer representing the answer. If it is impossible to cut the big chocolate k times, print -1. In the first sample, Jzzhu can cut the chocolate following the picture below: In the second sample the optimal division looks like this: In the third sample, it's impossible to cut a 2 xe2 x80 x89 xc3 x97 xe2 x80 x893 chocolate 4 times."...