Gresie

#include <bits/stdc++.h>

using namespace std;

int main()
{

    long long ra,rb,a,b,p;
    cin>>a>>b>>p;
    ra=a%p;
    rb=b%p;
    if(ra!=0){
        a=a+p-ra;
    }
    if(rb!=0){
        b=b+p-rb;
    }
    cout<<a*b/(p*p);
    return 0;
}