#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)
{
    int select;
    double data;
    
    reset();
    printf("1:+ 2:- 3:* 4:/ 5:data 9:answer\n");
    while(1){
        scanf("%d", &select);

        switch(select){
            case 1:
            {
                double b = pop();
                double a = pop();
                push(a + b);
                break;
            }

            case 2:
            {
                double b = pop();
                double a = pop();
                push(a - b);
                break;
            }

            case 3:
            {
                double b = pop();
                double a = pop();
                push(a * b);
                break;
            }

            case 4:
            {
                double b = pop();
                double a = pop();
                push(a / b);
                break;
            }

            case 5:
                scanf("%lf", &data);
                push(data);
                break;

            case 9:
                answer();
                return 0;
        }
    }

    return 0;
}


void push(double value)
{
    if(!isFull()){
        stack[sp] = value;
        sp++;
    }
}


double pop(void)
{
    if(!isEmpty()){
        sp--;
        return stack[sp];
    }

    return 0;
}


int isFull(void)
{
    if(sp >= SIZE){
        return 1;
    }
    return 0;
}


int isEmpty(void)
{
    if(sp <= 0){
        return 1;
    }
    return 0;
}


void answer(void)
{
    if(!isEmpty()){
        printf("answer = %f\n", pop());
    }
}


void reset(void)
{
    sp = 0;
}