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 = map(int, input().split())
L = len(str(m))
end = m
flag = False
while True:
    if w > (10 ** L - end) * k * L:
        w -= (10 ** L - end) * k * L
        end = 10 ** L
        L += 1
        #if w < L * k:
            #print(end - m)
            #flag = True
            #break
        #else:
            #w -= L * k
            #end = 10 ** L + 1
    else:
        end += w // (L * k)
        break

if not(flag):
    print(end - m)