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 erc(x) :
    an = 0
    for i in range(x) :
        an = an * 10 + 9
    return an
def s(x) :
    y = 0
    while x > 0 :
        y += 1
        x //= 10
    return y
cnt = 0
for i in range(s(m),30) :
    cnt += min(erc(i) - m + 1,w // (i * k))
    #print(erc(i))
    if(erc(i) - m + 1 >= w / (i * k)) :
        #print(min(erc(i) - m + 1 , w // (i * k)))
        #print(w , i)
        w -= (min(erc(i) - m + 1 , w // (i * k)) * k * i)
        #print(w)
        break
    #print(min(erc(i) - m + 1,w // (i * k)))
    w -= min(erc(i) - m + 1 , w // (i * k)) * k * i
    m = 1
    for j in range(i) :
        m = m * 10
    #print(m)
print(int(cnt))