import itertools
n, k = map(int, input().split())

if n >= 6:
    ans = n*(n+1)//2-(n-k)*(n+1-k)//2+1
    
else:
    li = [i+1 for i in range(n)]
    ans = []
    for ptn in itertools.product(range(2),repeat=n):
        if sum(ptn) <= k:
            cnt = 0
            for i in range(len(ptn)):
                if ptn[i] == 1:
                    cnt += li[i]
        ans.append(cnt)
    ans = set(ans)
    ans = len(ans)
print(ans)