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

def solve():
    w,m,k, = rv()
    small, large = 0, int(1e16)
    while small < large:
        avg = (small + large + 1) // 2
        if works(avg, w, m, k): small = avg
        else: large = avg - 1
    print(small)

def works(numbers, maxcost, startnum, multiplier):
    maxnumber = numbers + startnum - 1
    res = 0
    for length in range(1, 20):
        goodoflength = max(0, maxnumber - (pow(10, length - 1) - 1))
        badoflength = max(0, startnum - (pow(10, length - 1) - 1) - 1)
        res += (goodoflength - badoflength)
    return res * multiplier <= maxcost

def rv(): return map(int, input().split())
def rl(n): return [list(map(int, input().split())) for _ in range(n)]
if sys.hexversion == 50594544 : sys.stdin = open("test.txt")
solve()


