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 number_of_digits(n):
    if n == 0:
        return 0
    else:
        return 1 + number_of_digits(n//10)

def calc(n):
    if n <= 0:
        return 0
    d = number_of_digits(n)
    ret = 0
    for i in range(1,d):
        ret += 9*(10**(i-1))*i
    ret += (n-(10**(d-1))+1)*d

    return ret


def calc2(f,t):
    return calc(t) - calc(f-1)

def solve(w,m,k):
    lower = 0
    upper = m+w
    for i in range(100):
        mid = (lower+upper)//2
        cur = calc2(m,mid)

        if k*cur <= w:
            lower = mid
        else:
            upper = mid

    return lower - m + 1

def main():
    w,m,k = map(int,input().split())
    print(solve(w,m,k))

if __name__ == "__main__":
    main()
