Codeforces 1A Theatre Square

#include<iostream>

using namespace std;

int main()
{
    long long n,m,a;
    cin>>n>>m>>a;
    long long a1,a2;
    if(n%a!=0)
    {
        a1=n/a+1;
    }else
    {
        a1=n/a;
    }

    if(m%a!=0)
    {
        a2=m/a+1;
    }else
    {
        a2=m/a;
    }
    long long sum;
    sum=a1*a2;

    cout<<sum;


    return 0;
}