A 4 × 4 grid contains 16 points. You start at the top-left point and want to reach the bottom-right point.
Each move goes right along a row or down along a column. You may move any positive number of spaces, skipping points, but must land on a point in the grid. You cannot move left, up, or diagonally.
How many different routes are possible? Routes are different if their sequences of landing points differ.