We will first specify the syntax of a path. Let's define a direction letter as one of the four letters N, E, S, or W (representing north, east, south, and west), in either upper or lower case. A path segment is a direction letter followed by exactly zero, one, or two digit characters; examples are N and s2 and e13. A path is a sequence of zero or more path segments not separated or surrounded by spaces, commas, or anything else; every character in a non-empty path must be part of a path segment). An example of a path is N2e1Es2e1. Now for the semantics Meaning) of a path. Given a start position in a grid, a travelable path is a path that the robot could travel completely, starting from the start position, without starting on or trying to move to a grid point containing a wall or moving off the grid. By traveling a path, we mean interpreting the path segments, in order, as instructions to move the specified number of steps in the specified direction. (A direction letter followed by no digits means to move one step in that direction. As for two digits, the path segment w14