Notes

Template in C

Constraints

2 ≤ the number of operands in the expression ≤ 100
1 ≤ the number of operators in the expression ≤ 99
-1 × 109 ≤ values in the stack ≤ 109

Input

An expression is given in a line. Two consequtive symbols (operand or operator) are separated by a space character.

You can assume that +, - and * are given as the operator and an operand is a positive integer less than 106

Output

Print the computational result in a line.

Examples

Input

1 2 +


Output

3


Input

1 2 + 3 4 - *


Output

-3
#!/usr/bin/env python
#-*- coding:utf-8 -*-

def calc(n,m,ope):
	n = int(n)
	m = int(m)
	rslt = 0
	if ope == "+":
		rslt = n + m
	elif ope == "-":
		rslt = n - m
	elif ope == "*":
		rslt = n * m
	else:
		try:
			raise ValueError("invalid operator!")
		except ValueError as e:
			print(e)
	return rslt
		
def main():
	formula = raw_input().split()
	stack = []
	for f in formula:
		if f == '+' or f == '-' or f == '*':
			pop1 = stack.pop()
			pop2 = stack.pop()
			rslt = calc(pop2, pop1,f)
			stack.append(rslt)
		else:
			stack.append(f)
		
	print stack.pop()




#def test():

if __name__ == '__main__':
	main()
	#test()