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 = tuple(map(int,input().split()))
s = len(str(m))
t = m
n = 10 * s
r = (n - t) * s * k
while w >= r:
    w -= r
    t = n
    n *= 10
    s += 1
    r = (n - t) * s * k
if w != 0:
    n //= 10
    r = s * k
    while w >= r:
        w -= r
        n += 1
else: n //= 10
print(n - m)