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 fhelp(a):
    s = 1
    f = 10
    res = 0
    while a >= s:
        if (a >= s and a < f):
            break
        res += len(str(s)) * k * (f - s)
        s *= 10
        f *= 10  
    res += len(str(a)) * k * (a - s + 1)
    return res

def f(a, b):
    return fhelp(b) - fhelp(a - 1)
    
w, m, k = map(int, input().split())
w += fhelp(m - 1)
#print(fhelp(10))
summ = 0
power = 1
count = 9
while summ <= w:
    q = power * k * count
    if summ + q > w:
        break
    summ += q
    power += 1
    count *= 10
diff = w - summ
diff //= (power * k)
num = 10**(power - 1) + diff
print(num - m)