fact = [1]
for i in range(100):
    fact.append(fact[-1] * (i+1))

def IDtoL(L, id):
    n = len(L)
    if n == 0: return []
    l = [a for a in L]
    t = l.pop(id//fact[n-1])
    return [t] + IDtoL(l, id % fact[n-1])

def LtoID(L):
    n = len(L)
    if n == 1: return 0
    a =  len([l for l in L if l < L[0]])
    return a * fact[n-1] + LtoID(L[1:])

def rev(A):
    n = len(A)
    B = [-1] * n
    for i, a in enumerate(A):
        B[a] = i
    return B

N, S = map(int, input().split())
print(LtoID(rev(IDtoL([a for a in range(S)], N))))