#include <stdio.h>
#include <stdlib.h>

int main()
{

    double a,b,c,summe;

        while(1){

            scanf("%lf",&a);


         if(a == 0){

            break;

         }
            else{
                scanf("%lf %lf",&b,&c);

                summe = (a*b* c)/2;

                    printf("%.0lf paginas\n",summe);
            }

        }



    return 0;
}