We'll define S(n) for positive integer n as follows: the number of the n's digits in the decimal base. For example, S(893) = 3, S(114514) = 6.

You want to make a consecutive integer sequence starting from number m (m, m + 1, ...). But you need to pay S(n)·k to add the number n to the sequence.

You can spend a cost up to w, and you want to make the sequence as long as possible. Write a program that tells sequence's maximum length.

Input

The first line contains three integers w (1 ≤ w ≤ 1016), m (1 ≤ m ≤ 1016), k (1 ≤ k ≤ 109).

Please, do not write the %lld specifier to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specifier.

Output

The first line should contain a single integer — the answer to the problem.

Examples

Input

9 1 1


Output

9


Input

77 7 7


Output

7


Input

114 5 14


Output

6


Input

1 1 2


Output

0
# import sys; sys.stdin = open('input.txt')	#debug
import math
R = lambda: map(int, raw_input().split())

w, m, k = R()
if k == 0:
	print -1
	quit()

w = int(w/int(k))

if w is 0:
	print 0
	quit()

nrcifre = int(math.log(m)/math.log(10))

sol = 0
while w > 0:
	nrcifre = len(str(m))
	# print"w", w
	val = nrcifre*(10**nrcifre-m)
	if w >= val:
		sol += 10**nrcifre - m
		w -= val
		m = 10**nrcifre
		# print w
		# print "~", w, sol, val, nrcifre-1
	else:
		break
if w > 0:
	# print 'final', w, sol, nrcifre
	sol += w/nrcifre #10**(nrcifre-1), nrcifre)
# else:
# 	sol += cautare(m, nrcifre)
# else:
# 	print 'final2', w, sol, nrcifre
# 	sol += w/nrcifre
print sol