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

#define STACK_SIZE 10
#define BUFFER_SIZE 100

struct stack {
    float values[STACK_SIZE];
    int size;
};

void init_stack(struct stack* s) {
    s->size = 0;
}

int push_stack(struct stack* s, float znac) {
    if (s->size >= STACK_SIZE) {
        printf("stack overflow\n");
        return 0;
    }
    s->values[s->size++] = znac;
    return 1;
}

int pop_stack(struct stack* s, float* out) {
    if (s->size < 1) {
        printf("stack underflow\n");
        return 0;
    }
    *out = s->values[--s->size]; //зменшуємо розмір стеку
    return 1;
}

void print_stack(struct stack* s) {
    for (int i = 0; i < s->size; i++) {
        printf("%.2f ", s->values[i]);
    }
    printf("\n");
}

int main() {
    struct stack mystack;
    char buffer[BUFFER_SIZE];
    char operator;
    float new, a, b, result;
    init_stack(&mystack);  //обнуляємо стек

    while (fgets(buffer, BUFFER_SIZE, stdin)) {
        buffer[strcspn(buffer, "\n")] = '\0';
        if (strlen(buffer) == 0) {
            printf("no input\n");
            return 0;
        }

        if (sscanf(buffer, "%f", &new) == 1) {  //спроба прочитати число
            if (!push_stack(&mystack, new)) return 1;
            print_stack(&mystack);
        }else if (sscanf(buffer, " %c", &operator) == 1 && strchr("+-*/", operator)) {
            if (!pop_stack(&mystack, &b) || !pop_stack(&mystack, &a)) return 1;

            switch (operator) {
                case '+': result=a+b; break;
                case '-': result=a-b; break;
                case '*': result=a*b; break;
                case '/':
                    if (b == 0) {
                        printf("division by zero\n");
                        return 0;
                    }
                    result = a/b;
                    break;
            }

            if (!push_stack(&mystack, result)) {
                return 1;
            }
            print_stack(&mystack);
        } else {
            printf("bad input\n");
            return 0;
        }
    }
    printf("no input\n");
    return 0;
}