n = int(input())

fac_2n = 1
fac_n = 1

for i in range(1,2*n+1):
	fac_2n = fac_2n*i

for i in range(1,n+1):
	fac_n = fac_n*i

ans = fac_2n/(fac_n*fac_n*(n+1))

print(ans)