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.
import math
z = input().split()
w = int(z[0])
m = int(z[1])
k = int(z[2])

digs = int(math.log10(m))+1
# print("digits: {}".format(digs))
upper = int('9'*digs)
# print("upper: {}".format(upper))
ans = 0
while w > 0:
	if (upper-m+1)*digs*k <= w:
		# print(m, upper)
		w = w - (upper-m+1)*digs*k
		ans += (upper-m+1)
		digs += 1
		m = int('1'+ '0'*(digs-1))
		upper = int('9'*digs)
	else:
		ans += int(w/(k*digs))
		break

print(ans)
		