#include<stdio.h>
#include <stdlib.h>
int main(void){
     int X,Y;
    int L,n,m;
    scanf("%d",&X);
    scanf("%d",&Y);
    scanf("%d",&L);
     if(X%L!=0&&Y%L!=0){
         n=abs(X)/L+abs(Y)/L+2;
     }else if (X%L==0&&Y%L==0){
         n=abs(X)/L+abs(Y)/L;
     }else{
         n=abs(X)/L+abs(Y)/L+1;
     }

     
    if(Y>=0){
        if(X==0){
            m=n;
        }
        else{
            m=n+1;
        }
    }
    else{
            m=n+2;
        }
    printf("%d\n",m);
    return 0;

}