#! /usr/bin/env python
# -*- coding: utf-8 -*-
def main():
print('> ', end='')
cal = input().split()
stack = []
for c in cal:
if c.isdigit() == True:
stack.append(int(c))
elif len(stack) >= 2:
b = stack.pop()
a = stack.pop()
if c == '+':
stack.append(a + b)
elif c == '-':
stack.append(a - b)
elif c == '*':
stack.append(a * b)
elif c == '/':
if b == 0:
print('division by zero')
break
stack.append(a / b)
if len(stack) == 1:
print(stack.pop())
else:
print('error')
if __name__ == '__main__':
main()
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