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.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B solver = new B();
        int testCount = 1;
        for (int i = 1; i <= testCount; i++)
            solver.solve(i, in, out);
        out.close();
    }
}

class B {

    long nine[] = new long[19];
    long pow[] = new long[19];

    {
        nine[1] = 9;
        for(int i=2; i<19; i++) {
            nine[i] = nine[i-1]*10+9;
        }

        pow[0] = 1;
        for(int i=1; i<19; i++) {
            pow[i] = pow[i-1] * 10;
        }
    }

    public void solve(int testNumber, InputReader in, PrintWriter out) {
        long w = in.nextLong();
        long m = in.nextLong();
        long k = in.nextLong();

        int x = numDigit(m);

        //case 1
        BigInteger b = new BigInteger(String.valueOf(nine[x]-m+1));
        BigInteger kx = new BigInteger(String.valueOf(k * x));
        b = b.multiply(kx);
        BigInteger bw = new BigInteger(String.valueOf(w));
        if(b.compareTo(bw) >= 0) {
            out.println(w/(k*x));
            return;
        }

        long sol = nine[x] - m + 1;
        w = w - sol*x*k;
        x++;

        while (w >= k * x) {
            b = new BigInteger(String.valueOf(nine[x]-pow[x-1]+1));
            kx = new BigInteger(String.valueOf(k * x));
            b = b.multiply(kx);
            bw = new BigInteger(String.valueOf(w));
            long sol1 = 0;
            if(b.compareTo(bw) >= 0) {
                sol1 = w/(k*x);
            } else {
                sol1 = nine[x] - pow[x-1] + 1;
            }
            w = w - sol1*k*x;
            x++;
            sol += sol1;
        }
        out.println(sol);
    }


    private int numDigit(long m) {
        int ct = 0;
        while (m > 0) {
            m /= 10;
            ct++;
        }
        return ct;
    }
}

class InputReader {
    private BufferedReader reader;
    private StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

    public long nextLong() {
        return Long.parseLong(next());
    }
}

