def Exgcd (a, b):
	if b == 0:
		return 1, 0, a
	y, x, t = Exgcd (b, a % b)
	y -= a // b * x
	return x, y, t
b, d, a = input().split()
b = int(b)
d = int(d)
aa = int(a)
"""
if d == 0:
	two, five = 0, 0
	w = b
	while w % 2 == 0:
		w //= 2
		two += 1
	while w % 5 == 0:
		w //= 5
		five += 1
	while two != five:
		if two < five:
			if b * 2 <= aa:
				b *= 2
				two += 1
			else:
				break
		else:
			if b * 5 <= aa:
				b *= 2
				five += 1
			else:
				break
	while b * 10 <= aa:
		b *= 10
		two += 1
		five += 1
	print(min(two, five))
	exit(0)
"""

def check(X):
	ddd = 0
	for i in range(X):
		ddd = (ddd * 10 + d) % b
	ttt = pow(10, X, b)
	x, y, g = Exgcd (ttt, b)
	if (b - ddd) % g != 0:
		return False
	xstep = b // g
	ystep = ttt // g
	minx = None
	if x < 0:
		need = (-x + xstep - 1)// xstep
		minx = x + need * xstep
	else:
		minx = x % xstep
	# print ("minx before", minx)
	minx *= (b - ddd) // g
	minx %= xstep
	if d == 0 and minx == 0:
		minx = xstep
	# print ("check : ", X, minx)
	first = minx * pow(10, X)
	if first > aa:
		return False
	ddd = 0
	for i in range(X):
		ddd = ddd * 10 + d
	# print ("solution is ", first + ddd)
	return first + ddd <= aa
l, r = 0, len(a)
while l < r:
	mid = (l + r + 1) // 2
	if check(mid):
		l = mid
	else:
		r = mid - 1
print(l)