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.
The first line contains three integers *w* (1 ≤ *w* ≤ 10<sup class="upper-index">16</sup>), *m* (1 ≤ *m* ≤ 10<sup class="upper-index">16</sup>), *k* (1 ≤ *k* ≤ 10<sup class="upper-index">9</sup>).

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.
# https://codeforces.com/contest/373/problem/B

import sys
read = sys.stdin.readline
write = sys.stdout.write

w,m,k = map(int, read().split())
ans = 0

dig = 1
while 10**dig <= m:
	dig += 1
# write(str(dig))

while True:
	if 10**dig == m:
		dig += 1
	req = dig * k
	if w >= req:
		w -= req
		ans += 1
		# write("We added " + str(m) + '\n')
		# write("We have " + str(w) + " coins left\n\n")
	else:
		break
	m += 1

write(str(ans))