import operator as op
 
table = {'+' : op.add, '-' : op.sub, '*' : op.mul, '/' : op.truediv}
 
def rpn(exp):
    stack = []
    for token in exp.split():
        try: stack += [int(token)]
        except ValueError:
            try: stack += [float(token)]
            except ValueError:
                stack = stack[:-2] + [table[token](*stack[-2:])]
    return stack[-1]
 
if __name__ == '__main__':
    exp = "6.1 5.2 4.3 * + 3.4 2.5 / 1.6 * -"
    ans = rpn(exp)
    print("{0} = {1:.4f}".format(exp, ans))
 

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