spoj#VNACM14H. Pencil Game
Pencil Game
  Minh has a box of pencils. The box is a rectangle of size M ĂN, where position (i, j) has a pencil  with a length of exactly i Ă N + j (0 ⤠i ⤠M-1, 0 ⤠j ⤠N-1). Note that position (0, 0) does not have any pencil hence having a length of 0.
  He wonders if he could select a sub-rectangle of the box and join all the pencils within that sub-rectangle together, to get a new long pencil that has a specific length L that he wants.
  Your task is to find a sub-rectangle of the box in which the total length of the contained pencils is L and return the area of that the sub-rectangle. If there are multiple solutions, return the smallest  possible area. If thereâs no such sub-rectangle, return -1.
Input
The input file consists of several datasets. The first line of the input file contains the number of
datasets which is a positive integer and is not greater than 150. The following lines describe theÂ
datasets.
  Each dataset contains three space-separated numbers M, N and L (1 ⤠M, N ⤠10^6, 1 ⤠L ⤠10^12) written in one line.
Output
  For each dataset, write in one line the smallest possible area of the sub-rectangle in which the total sum of pencil lengths is L. Write in one line -1 if there is no such sub-rectangle.
Example
Input: 2 2 3 8 2 2 7
Output: 4 -1