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.

Input

The first line contains three integers w (1 ≤ w ≤ 1016), m (1 ≤ m ≤ 1016), k (1 ≤ k ≤ 109).

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.

Output

The first line should contain a single integer — the answer to the problem.

Examples

Input

9 1 1


Output

9


Input

77 7 7


Output

7


Input

114 5 14


Output

6


Input

1 1 2


Output

0

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.math.BigInteger;
import java.util.Scanner;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author mark
 */
public class SeqFun {

    public static void main(String[] args) throws FileNotFoundException {
        //FileInputStream file = new FileInputStream(new File("/home/mark/tmp/input.txt"));
        //Scanner scan = new Scanner(file);

        Scanner scan = new Scanner(System.in);

        BigInteger w = BigInteger.valueOf(scan.nextLong());
        BigInteger m = BigInteger.valueOf(scan.nextLong());
        BigInteger k = BigInteger.valueOf(scan.nextLong());
        BigInteger s = BigInteger.valueOf(m.toString().length());
        
        if (k.compareTo(w) > 0) {
            System.out.println("0");
            return;
        }

        BigInteger n = BigInteger.valueOf((long)Math.pow(10,s.intValue()));

        BigInteger diff = n.subtract(m);
        //int i = 0;

        BigInteger counter = BigInteger.ZERO;
        boolean done = false;

        while (!done) {
            if (w.compareTo(s.multiply(k).multiply(diff))<0) {
                diff = w.divide(s.multiply(k));
                counter= counter.add(diff);
                done = true;
            } else {
                counter= counter.add(diff);
                BigInteger adj = k.multiply(s).multiply(diff);
                w=w.subtract(adj);
                s=s.add(BigInteger.ONE);
                diff = BigInteger.valueOf((long)(Math.pow(10, s.longValue()) - Math.pow(10, s.longValue() - 1)));
            }
        }
        System.out.println(counter);
    }
}
