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

#define STACK_SIZE 10

float stack[STACK_SIZE];
int stack_top = -1;

bool is_number(char *string) {
    char *end;
    strtof(string, &end);
    return end != string && (*end == '\n' || *end == '\0');
}

bool is_operation(char *string) {
    return strlen(string) == 2 && (string[0] == '+' || string[0] == '-' || string[0] == '*' || string[0] == '/');
}

float calculator(float n1, float n2, char operation) { 
    if (operation == '+') {
        return n1 + n2;
    }
    else if (operation == '-') {
        return n1 - n2;
    }
    else if (operation == '*') {
        return n1 * n2;
    }
    else if (operation == '/') {
        if (n2 != 0) {
            return n1 / n2;
        } else {
            printf("division by zero\n");
            exit(0);
        }
    }
    return 0;
}

void push(float number) {
    if (stack_top < STACK_SIZE - 1) {
        stack[++stack_top] = number;
    } else {
        printf("full stack\n");
        exit(0);
    }
}

float pop() {
    if (stack_top >= 0) {
        return stack[stack_top--];
    } else {
        printf("stack is empty\n");
        exit(0);
    }
}

void print_stack() {
    for (int i = 0; i <= stack_top; i++) {
        printf("%.2f", stack[i]);
        if (i < stack_top) {
            printf(" ");
        }
    }
    printf(" \n");
}

int main() {
    char arr[50];
    char *pend;
    stack_top = -1;

    while (fgets(arr, 50, stdin)) {
        if (arr[0] == '\n' || arr[0] == EOF) {
            break;
        }

        if (is_number(arr)) {
            float number = strtof(arr, &pend);
            push(number);
            print_stack();
        }
        else if (is_operation(arr)) {
            if (stack_top < 1) {
                printf("not enough operands\n");
                return 0;
            }

            float n2 = pop();
            float n1 = pop();
            char operation = arr[0];
            float result = calculator(n1, n2, operation);
            push(result);
            print_stack();
        }
        else {
            printf("bad input\n");
            return 0;
        }
    }

    printf("no input\n");

    return 0;
}