<s>[INST] This problem is related to dynamic programming. A robot is placed on a grid with r rows and c columns. The robot can move either to the left, right, up, or down, and the only constraint is that the robot can never move to a cell that it has already visited before. In other words, the robot can only visit each cell at most once. The robot starts at the top-left cell, which is at (0,0). Please find the number of unique paths that the robot can take to reach the bottom-right cell, which is at (r-1, c-1), and print out the result.[/INST]