#include <stdio.h>

#define SIZE 10
double stack[SIZE];
int sp;

void push(double value);
double pop(void);
int isFull(void);
int isEmpty(void);
void answer(void);
void reset(void);


int main(void) {

reset();
while(1){
double data,a,b;
int resp;
if (scanf("%d", &resp) != 1 || !resp) {
            break;}
switch(resp){
  case 1:a=pop();
         b=pop();
         push (b+a);
         break;
  case 2:a=pop();
         b=pop();
         push (b-a);
        break;
  case 3:a=pop();
         b=pop();
         push (b*a);
         break;
  case 4:a=pop();
         b=pop();
         push (b/a);
         break;
  case 5:scanf("%lf",&data);
         printf("data:%lf\n",data);
         push (data);
        break;
  case 9:answer();
              break;
 default:
     break;
  }
}
    answer();
    return 0;
}
void push(double value)
{
 if (!isFull())
 {
    stack[sp]=value;
    sp++;
  }
}
double pop(void)
{
  if (!isEmpty())
  {
    sp--;
   return stack[sp];
   }
}
int isFull(void)
{
 return sp >= SIZE;
}
int isEmpty(void)
{
 return sp <= 0;
}
void answer(void)
{
    if (sp > 0) {
        printf("answer: %f\n", stack[sp - 1]);
    }
}
void reset(void)
{
    sp = 0;
}

	// your code goes here