B = int(input())
D = int(input(), base=B) - 1

def f(k):
  return (B**k-1-(B-1)*B**k*k)//(1-B)

l = 0
r = 100000
while r - l > 1:
  m = (l + r) // 2
  if D >= f(m):
    l = m
  else:
    r = m
D -= f(l)

a, b = D // r + B**(r - 1), D % r

print(a // B**(r - 1 - b) % B)