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

#define SIZE 10

int main(void) {
    double ulozisko[SIZE];
    int top = 0;
    char vstup[64];

    while (fgets(vstup, sizeof(vstup), stdin)) {
        vstup[strcspn(vstup, "\n")] = 0;

        if (strlen(vstup) == 0) {
            printf("no input\n");
            return 0;
        }

        char *koniec;
        double cislo = strtod(vstup, &koniec);

        if (*koniec == '\0') {
            if (top >= SIZE) {
                printf("stack full\n");
                return 0;
            }
            ulozisko[top++] = cislo;
        } 
        else if (strlen(vstup) == 1 && strchr("+-*/", vstup[0])) {
            if (top < 2) {
                printf("not enough values\n");
                return 0;
            }
            double b = ulozisko[--top];
            double a = ulozisko[--top];
            double vysledok = 0.0;

            switch (vstup[0]) {
                case '+': vysledok = a + b; break;
                case '-': vysledok = a - b; break;
                case '*': vysledok = a * b; break;
                case '/': vysledok = b == 0 ? (printf("division by zero\n"), exit(0), 0) : a / b; break;
                default: printf("invalid op\n"); return 0;
            }

            ulozisko[top++] = vysledok;
        } 
        else {
            printf("invalid input\n");
            return 0;
        }

        for (int i = 0; i < top; i++)
            printf("%.2f ", ulozisko[i]);
        printf("\n");
    }

    printf("no input\n");
    return 0;
}