Tren is a logic puzzle invented by Shinichi Aoki (Japan). The Japanese name of this puzzle means "parking" (each block is a car, and a grid is a car park). The puzzle contains a grid with numbers in some cells. The goal is to locate some blocks in the grid, having the size either 1 x 2 or 1 x 3. Each number in the grid should be part of a block, indicating the amount of the possible movements of the block. Blocks can only move in the direction of their short edge.