CF_1A Theatre Square

#include<iostream>

using namespace std;

int main()
{
    long long a,m,n,x,y,sum;
    while(cin>>n>>m>>a)
    {
        x=0;y=0;sum=0;
    if((m>=a))
    {
        x=m/a+1;
        if(m%a==0) x--;

    }
    else if(m<a) x=1;


    if(n>=a)
    {
        y=n/a+1;
        if(n%a==0) y--;
    }
    else if(n<a) y=1;


    sum=x*y;
    cout<<sum<<endl;
    }

}