#include <stdio.h>
#include <stdlib.h> /* atof() */

#define MAXOP 100
#define NUMBER '0'

int getop(char []);
void push(double);
double pop(void);

/* Polish calc */
int main (void){
    int type;
    double op1, op2;
    char s[MAXOP];

    while( (type = getop(s)) != EOF ){
        switch(type){
            case NUMBER:
                push(atof(s));
                break;
            case '+':
                push(pop() + pop());
                break;
            case '*':
                push(pop() * pop());
                break;
            case '-':
                op2 = pop();
                push(pop() - op2);
                break;
            case '/':
                op2 = pop();
                if(op2 != 0.0)
                    push(pop() / op2);
                else
                    printf("Divide by zero!\n");
                break;
            case '%':
                op2 = pop();
                op1 = pop();
                push( (int) op1 - (int) op2 * ( (int) op1 / (int) op2 ) );
            case '\n':
                printf("%.4g\n", pop());
                break;
            default:
                printf("Unknown operation, %s\n", s);
                break;
        }
    }
    return 0;
}

#define MAXVAL 100 //Stack depth
int sp = 0; //Next free stack position
double stack[MAXVAL];

/* Put into stack */
void push(double f){
    if(sp < MAXVAL)
        stack[sp++] = f;
    else
        printf("Stack overflow\n");
}

/* Take out of stack */
double pop(void){
    if(sp > 0){
        return stack[--sp];
    }
    else{
        printf("Stack underflow\n");
        return 0.0;
    }
}

#include <ctype.h> /* isdigit(), iswhite() */
int getch(void);
void ungetch(int);

/* Analizes input */
int getop(char s[]){
    int i, c;

    while((s[0] = c = getch()) == ' ' || c == '\t')
        ;
    s[1] = '\0';
    if(!isdigit(c) && c != '.')
        return c; //Not a number
    i=0;
    if(isdigit(c))
        while(isdigit(s[++i] = c = getch()))
            ;
    if(c == '.')
        while(isdigit(s[++i] = c = getch()))
            ;
    s[i] = '\0';
    if(c!=EOF)
        ungetch(c);
    return NUMBER;
}

#define BUFSIZE 100
char buf[BUFSIZE];
int bufp = 0;

int getch(void){
    return (bufp > 0) ? buf[--bufp] : getchar();
}

void ungetch(int c){
    if(bufp > BUFSIZE)
        printf("Too much symbols");
    else
        buf[bufp++] = c;
}