import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

B = int(readline())
D_str = read().rstrip()
n = len(D_str)
D = int(D_str, B)


def f(B, n):
    """sum k=1,...,n k(B^k-B^{k-1})"""
    x = B ** n
    return (x * (n * B - n - 1) + 1) // (B - 1)


for k in range(n - 20, n + 20):
    if k < 0:
        continue
    #  k桁までの消費
    if f(B, k) >= D:
        break

rest = D - f(B, k - 1)
q, r = divmod(rest, k)
num = B ** (k - 1) + q
num //= (B ** (k - r))
print(num % B)