#include <stdio.h>

#define PI 3.1415927
//---------------------------------------------------------------------------
int main(int argc, char **argv)
{
  int volba;
  float a,b;
  do
  {
    printf("1 ... Zadani stran\n");
    printf("2 ... Obsah\n");
    printf("3 ... Obvod\n");
    printf("4 ... Konec\n");
    printf("---------------------\n");
    printf("Volba: ");
    volba= 0;
    scanf("%d",&volba);
    switch (volba)
    {
	  case 1: printf("Zadej strany: ");
           	  scanf("%f %f",&a,&b);
              printf("a = %f, b = %f\n\n",a,b);
              break;
      case 2: printf("Obsah: %.2f\n\n", a*b);
              break;
      case 3: printf("Obvod: %.2f\n\n", 2*(a+b));
              break;
    }
  } while (volba!= 4);
  return 0;
}