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 = list(map(int, input().split()))

ans = 0; c = 0
n = 0
while 10 ^ n < m:
    n += 1

if (10 ^ n - m) * n * k >= w:
    print(w // (n * k))
    exit()
else:
    c += (10 ^ n - m) * n * k
    ans += 10 ^ n - m
n += 1

while c + 10 ^ (n - 1) * 9 * n * k  <= w:
    c += 10 ^ (n - 1) * 9 * n * k
    ans += 10 ^ (n - 1) * 9
    n += 1
ans += (w - c) // (n * k)

print(ans)