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.
(w, m, k) = (int(string) for string in input().split())
answer = 0
digitCount = len(str(m))
while w > 0:
    ceiling = 10**digitCount
    numberCountInThisLength = ceiling - m
    cost = digitCount * k * numberCountInThisLength
    if w > cost:
        w -= cost
        answer += numberCountInThisLength
        m = ceiling
        digitCount += 1
    else:
        answer += w / (k*digitCount)
        break

print('%d' % answer)
