cf 1a Theatre Square

#include <iostream>
#include <cstdio>
using namespace std;
int main()
{
    long long n,m,a,b,c;
    scanf("%lld%lld%lld",&n,&m,&a);
    b=(n-1)/a+1;
    c=(m-1)/a+1;
    printf("%lld\n",b*c);
}