#include <stdio.h>
#include <stdlib.h>

int main(){
    int EW, NS;
    int dt, cnt = 0;

    scanf("%d %d %d", &EW, &NS, &dt);
    if(NS < 0)  cnt += 2;
    if(NS%dt == 0){
        cnt += NS/dt;
    }else{
        cnt += NS/dt + 1;
    }

    if(EW != 0) cnt++;
    if(EW%dt == 0){
        cnt += abs(EW)/dt;
    }else{
        cnt += abs(EW)/dt + 1;
    }

    printf("%d\n", cnt);

    return 0;
}