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())


def f(N):
    ANS = 0
    for keta in range(1, 20):
        lo = 10**(keta - 1)
        hi = min(N, 10**keta - 1)
        cnt = max(hi - lo + 1, 0)
        ANS += keta * cnt
    return ANS


ok = 0
ng = 1 << 100
while ok + 1 < ng:
    x = (ok + ng) // 2
    if (f(M + x - 1) - f(M - 1)) * K <= W:
        ok = x
    else:
        ng = x
print(ok)
