#include <stdio.h>

#define SIZE 10

double stack[SIZE];
int top = 0;

void push(double value)
{
    if(top == SIZE){
        printf("Stack is full\n");
        return;
    }

    stack[top] = value;
    top++;
}

double pop(void)
{
    if(top == 0){
        printf("Stack is empty\n");
        return 0;
    }

    top--;
    return stack[top];
}

void showAnswer(void)
{
    int i;
    double sum = 0;

    if(top == 0){
        printf("Stack is empty\n");
        return;
    }

    for(i = 0; i < top; i++){
        printf("Data %d: %g\n", i + 1, stack[i]);
        sum += stack[i];
    }

    printf("Answer %g\n", sum);
}

int main(void)
{
    int command;
    double data;
    double a, b;

    while(1){

       

        if(scanf("%d", &command) != 1){
            printf("Invalid input\n");
            break;
        }

        if(command == 0){
            break;
        }

        switch(command){

            case 1:
                if(top < 2){
                    printf("Not enough data in stack\n");
                    break;
                }

                b = pop();
                a = pop();
                push(a + b);
                break;

            case 2:
                if(top < 2){
                    printf("Not enough data in stack\n");
                    break;
                }

                b = pop();
                a = pop();
                push(a - b);
                break;

            case 3:
                if(top < 2){
                    printf("Not enough data in stack\n");
                    break;
                }

                b = pop();
                a = pop();
                push(a * b);
                break;

            case 4:
                if(top < 2){
                    printf("Not enough data in stack\n");
                    break;
                }

                b = pop();
                a = pop();

                if(b == 0){
                    printf("Cannot divide by zero\n");
                    push(a);
                    push(b);
                    break;
                }

                push(a / b);
                break;

            case 5:
               

                if(scanf("%lf", &data) != 1){
                    printf("Invalid input\n");
                    return 1;
                }

                push(data);
                break;

            case 9:
                showAnswer();
                break;

            default:
                printf("Invalid command\n");
                break;
        }
    }

    return 0;
}