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
/**
 * Created with IntelliJ IDEA.
 * User: igar
 * Date: 14.12.13
 * Time: 16:15
 * To change this template use File | Settings | File Templates.
 */
import java.math.BigInteger;
import java.util.Scanner;

public class CF219_B {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.next();
        BigInteger w = new BigInteger(s);
        s = scanner.next();
        BigInteger m = new BigInteger(s);
        long k = scanner.nextInt();
        BigInteger n = BigInteger.ZERO;
        BigInteger exp = BigInteger.TEN;
        while (true) {
            if (m.compareTo(exp) == -1) {    // m < exp
                BigInteger add = exp.subtract(m);
                BigInteger cost = add.multiply(BigInteger.valueOf(k * S(m)));
                if (w.compareTo(cost) == -1)
                    add = w.divide(BigInteger.valueOf(k * S(m)));
                n = n.add(add);
                m = exp;
//                System.out.println("n = " + n + ", add = " + add + ", cost = " + cost + ", w = " + w + ", exp = " + exp + ", m = " + m);
                w = w.subtract(cost);
                if (w.signum() <= 0) {
                    System.out.println(n);
                    break;
                }
            }
            exp = exp.multiply(BigInteger.TEN);
        }
    }

    public static int S(BigInteger bigInteger) {
        return bigInteger.toString().length();
    }
}