def power(p,n):
    if n == 0:
        return 1
    elif n%2==0:
        return power(p*p,n/2)
    else:
        return power(p,n-1)*p

B = int(input())
D = int(input(), B)
D += 1
if D <= B:
    print(D-1)
    exit(0)
inf = -1
sup = 100001
while sup-inf > 1:
    mid = (sup+inf)//2
    v = mid*power(B, mid)
    if v < D:
        inf = mid
    else:
        sup = mid


# print(inf,sup)
D -= inf*power(B,inf)
D -= 1
num = D//sup
d = D%sup
NUM = power(B,inf)+num
# print(NUM)
NUM //= power(B,inf-d)
# print("d=",d)
print(NUM%B)