"""
Starting in the top left corner of a 2 X 2 grid,
and only being able to move to the right and down,
there are exactly 6 routes to the bottom right corner.

How many such routes are there through a 20 X 20 grid?
"""

import math


def grid_paths(m: int, n: int) -> int:
    return math.comb(m + n, m)


def main() -> None:
    print(grid_paths(20, 20))


if __name__ == "__main__":
    main()