from stack import Stack
import math
import sys


#binary operators
def add(a, b):
    return a + b

def multiply(a, b):
    return a * b

def divide(a, b):
    return a / b

def subtract(a, b):
    return a - b

#unary operators
def negate(a):
    return -a

def square_root(a):
    return math.sqrt(a)

bin_ops = {'+':add,
            '-':subtract,
            '*':multiply,
            '/':divide}

unary_ops = {'n':negate,
            'r':square_root}

def calculator(line):

    tokens = line.split()

    stack = Stack()

    for t in tokens:
        if t not in bin_ops and t not in unary_ops:
            stack.push(float(t))
        elif t in bin_ops:
            b = stack.pop()
            a = stack.pop()
            stack.push(bin_ops[t](a, b))
        else:
            a = stack.pop()
            stack.push(unary_ops[t](a))

    return stack.top()

def main():

    for line in sys.stdin:
        try:
            a = calculator(line.strip())
            print('{:.2f}'.format(a))
        except IndexError:
            print('Invalid RPN expression')

if __name__ == '__main__':
    main()



#Stack class

class Stack(object):

    def __init__(self):
        self.l = []

    def push(self, e):
        self.l.append(e)

    def pop(self):
        return self.l.pop()

    def top(self):
        return self.l[-1]

    def is_empty(self):
        return len(self.l) == 0

    def __len__(self):
        return len(self.l)