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())
z=m
dig=0
while z>0:
	dig+=1;
	z=z//10
if(dig*k>w):
	print(0)
	exit(0)
lo=m-1
hi=w+m+5
while lo+1<hi:
	mid=(lo+hi)//2
	cost, t, d=0,0,0
	x=mid
	while x>0:
		x=x//10
		d+=1
	if(d==dig):
		cost=(mid-m+1)*d*k
	else:
		t=pow(10, dig)
		last=m
		c=dig
		while t<=mid:
			cost+=(t-last)*c*k
			c+=1
			last=c
			t=t*10
		t=t//10
		cost+=(mid-t+1)*c*k
	if(cost<=w):
		lo=mid
	else:
		hi=mid
print(lo-m+1)
