#include <stdio.h>
int X,Y,L,C;
int main(void){
    scanf("%d",&X);
    scanf("%d",&Y);
    scanf("%d",&L);
    if(X!=0){
        if(X<0)X*=-1;
        C+=2+(X-1)/L;
    }
    if(Y!=0){
        if(Y<0){Y*=-1;C++;}
        C+=1+(Y-1)/L;
    }
    printf("%d\n",C);
    return 0;
}