On the coordinate line, the points with coordinates $0,1,2, \ldots, 2 n-1$ are marked, where $n$ is a positive integer. A flea starts jumping from the point with coordinate 0 and after $2 n$ jumps returns there, having visited all the marked points. It is known that the total length of all jumps except the last one is $n(2 n-1)$. Find the length of the last jump.