m, n = map(int, input().split())
mf = 1
nf = 1
mnf = 1
for i in range(1, m+n-1):
    mnf *= i

for i in range(1, m):
    mf *= i

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

ans = mnf//(mf * nf)
print(ans)