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=input().split()
w=int(w)
m=int(m)
k=int(k)
ans=0
clen=len(str(m))
while (w>0):
    mx=pow(10,clen)-1
    diff=mx-m+1
    cost=clen*diff*k
    if(w>=cost):
        w-=cost
        ans+=diff
    else:
        diff=w//clen
        diff=diff//k
        ans+=diff
        break
    clen+=1
    m=mx+1
    
print(ans)    
