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.
def f(x):
    digs = len(str(x))
    
    ndig = digs*(x - 10**(digs-1) + 1)
    for i in range(1, digs):
        ndig += i * 9*10**(i-1)
    return ndig

a, b, c = map(int, input().split(' '))
num = a // c

need = num + f(b-1)

lo = 0
hi = 10**18

while lo < hi:
    mid = (lo + hi + 1) // 2
    if f(mid) > need:
        hi = mid - 1
    else:
        lo = mid
print(lo-b+1)
