import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int X = sc.nextInt();
        int Y = sc.nextInt();
        int L = sc.nextInt();
        int turn=0;
        int gox=0;
        int goy=0;

        if(X%L==0){
                gox=X/L;
        }else{
                gox=X/L+1;
        }
        if(Y%L==0){
                goy=Y/L;
        }else{
                goy=Y/L+1;
        }

        if(Y!=0){
                turn=1;
        }
        if(X<0){
                turn=turn+1;
        }

        int r = gox+goy+turn;
        System.out.println( r );
    }
}