def gcd(a, b):
    if b == 0:
        return a
    return gcd(b, a % b)

def exgcd(a, b):
    if b == 0:
        return 1, 0
    else:
        y, x = exgcd(b, a % b)
        y -= a // b * x
        return x, y

def check(mid, b, d, a):
    c = 0
    e = 1
    for i in range(0, mid):
        c = c * 10 + d
        e = e * 10
    # print(c)
    g = gcd(b, e)
    if c % g != 0:
        return False
    x, y = exgcd(b, e)
    y = -y
    # print(x, y, x * b - e * y)
    x = x * (c // g)
    y = y * (c // g)
    if b * x -  e * y < 0:
        x = -x
        y = -y
    # print(x, x * b, y * e, c, b * x - e * y)
    dx, dy = e // abs(g), b // abs(g)
    y = (y % dy + dy) % dy
    x = (c + e * y) // b
    if x == 0:
        x += dx
    # print(x, x * b, y * e, c, b * x - e * y)
    return x * b <= a

if __name__ == '__main__':
    x = input().split()
    b, d, A = int(x[0]), int(x[1]), x[2]
    a = 0
    for s in A:
        a = a * 10 + int(s)

    l, r = 0, 10000
    ans = 0
    while l <= r:
        mid = (l + r) // 2
        if check(mid, b, d, a):
            ans = mid
            l = mid + 1
        else :
            r = mid - 1

    print(ans)