# Starting in the top left corner of a 2×2 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 20×20 grid?

from scipy.special import binom

def solution():
    return binom(40, 20)


if __name__ == '__main__':
    print(solution())
