import java.io.*;
import java.util.regex.*;

class Process {
    private int X;
    private int Y;
    private int L;

    Process(int X, int Y, int L) {
        this.X = X;
        this.Y = Y;
        this.L = L;
    }

    private int moveCount(int n) {
        if(n < 0) {
            n *= (-1);
        }
        
        return (int)Math.ceil((double)n / L);
    }

    int getResult() {
        if((X == 0) && (Y >= 0)) {
            return moveCount(Y);
        }

        int rotateCount = (Y >= 0) ? 1 : 2;

        return (moveCount(X) + moveCount(Y) + rotateCount);
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        var bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        var printWriter = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

        // 入力
        int X = Integer.parseInt(bufferedReader.readLine().trim());

        int Y = Integer.parseInt(bufferedReader.readLine().trim());

        int L = Integer.parseInt(bufferedReader.readLine().trim());

        // 処理および出力
        printWriter.println((new Process(X, Y, L)).getResult());
        
        bufferedReader.close();
        printWriter.close();
    }
}