#include<bits/stdc++.h>
using namespace std;
int main(){
    int x,y,l,ans=0;
    cin>>x>>y>>l;
    if(y>=0){
        if(x!=0)++ans;
    }
    else{
        ans+=2;
    }
    ans+=ceil(fabs(x)/l);
    ans+=ceil(fabs(y)/l);
    cout<<ans<<endl;
}