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.
import sys
input = sys.stdin.readline


def f(x):
    a = len(str(m))
    b = len(str(x))
    c = 0
    q = m
    for i in range(a, b):
        d = 10**a
        c += (d - q)*k*i
        q = d
    c += (x+1-q)*k*b
    return c


w, m, k = map(int, input().split())
if w < k:
    print(0)
else:
    l, h = 1, w//k+m + 1
    t = 100
    ans = 0
    while t:
        mid = (l+h)//2
        ew = f(mid)
        if ew > w:
            h = mid
        elif ew < w:
            l = mid
            ans = max(ans, mid-m+1)
        else:
            ans = max(ans, mid-m+1)
            break
        t -= 1
    print(ans)