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())
cost, num = 0, 0
ln = len(str(m))
aim = 10**ln
if (aim - m)*ln*k <= w:
    cost += (aim - m)*ln*k
    num += (aim - m)*ln
    m = aim
    ln += 1

    while True:
        if ln*k*9*10**(ln-1)+cost <= w:
            cost += ln*k*9*10**(ln-1)
            num += 9*10**(ln-1)
            m = 10**ln
            ln += 1
        else:
            break
lastm = m
aim = 10**ln
mid, lastn = 0, 0
while aim != m+1:
    mid = m + (aim-m)//2
    if ln*k*(mid-lastm)+cost <= w:
        m = mid
    else:
        aim = mid
print(num + m - lastm)