#include<stdio.h>
#include<assert.h>
#include<string.h>
#include<stdlib.h>
#include<ctype.h>
#define STACK_SIZE 10

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

void push_stack(struct stack* mystack, float value)
{
    assert(mystack->size<STACK_SIZE);
    mystack->values[mystack->size]=value;
    mystack->size+=1;
}

int switch_operators(const char input[])
{
	if(strlen(input)==1)
	{
    switch (input[0])
    {
    case '+':
        return 0;
        break;
    case '-':
        return 0;
        break;
    case '*':
        return 0;
        break;
    case '/':
        return -1;
        break;
    }   
	}
	return 1;
}

float pop_stack(struct stack* mystack,const char input[])
{
    assert(mystack->size>1);
    float val1=mystack->values[mystack->size-2];
    float val2=mystack->values[mystack->size-1];
    switch (input[0])
    {
    case '+':
        mystack->size-=2;
        return val1+val2;
        break;
    case '-':
        mystack->size-=2;
        return val1-val2;
        break;
    case '*':
        mystack->size-=2;
        return val1*val2;
        break;
    case '/':
        mystack->size-=2;
        return val1/val2;
        break;
    default:
        break;
    }
}

void print_stack(struct stack* mystack)
{
    for(int i=0;i<mystack->size;i++)
    {
        printf("%.2f",mystack->values[i]);
        if (i<mystack->size-1)
        {
            printf(" ");
        }
    }
    printf(" \n");
}

int is_whitespace(const char* str) {
	    while (*str) 
	    {
		            if (!isspace((unsigned char)*str)) 
			    {
				                return 0;
                            }
			    str++;
	    }
	    return 1;
}

int main()
{
        struct stack mystack;
        memset(&mystack,0,sizeof(struct stack));
        char input[1000];
        while (fgets(input,sizeof(input),stdin)!=NULL)
        {	
            int flag=switch_operators(input);
            input[strcspn(input,"\n")]=0;
            if (flag==0 || flag==-1)
            {
			if(flag==-1 && mystack.values[mystack.size-1]==0)
			{
				printf("division by zero\n");
				return 0;
			}
                float op_num=pop_stack(&mystack,input);
                push_stack(&mystack,op_num);
            }
            else
            {
                char* ptr;
		if (*ptr!='\0' && !is_whitespace(ptr)) 
		{
                	printf("bad input\n");
                	return 0;
            	}
                float num=strtof(input,&ptr);
                push_stack(&mystack,num);
            }
            print_stack(&mystack);
        }
	printf("no input\n");
        return 0;
}