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

int main()
{

    double a,b,c,summe;

        while(1){

            scanf("%lf %lf %lf", &a,&b,&c);

         if(a == 0){

            break;

         }
            else{

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

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

        }



    return 0;
}