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.
lst = input().split()
lst = [int(x) for x in lst]
w, m , k = lst[0], lst[1], lst[2]

idx = 10
ans = 0
start = 1 
while idx <= m:
    start+=1
    idx*=10

while w:
    tmpc = start * (idx - m ) * k;
    # print(f"{m} {idx} {start} {tmpc}")
    if tmpc < w:
        ans+= (idx - m )
        w -= tmpc
        m = idx
        idx*=10
        start+=1
    else:
        ans += w // (start * k);
        break;

print(ans)