Codeforces 1A - Theatre Square Solution

Source :Ceil function

Solve in C:

#include<stdio.h>
#include<math.h>
int main()
{
    double m,n,a,r;
    scanf("%lf%lf%lf",&m,&n,&a);
    r=ceil(m/a)*ceil(n/a);
    printf("%.0lf\n",r);

}