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
def calc(stack, s):
	a = stack.pop()
	b = stack.pop()
	if s=='+':
		stack.append(b+a)
	elif s=='-':
		stack.append(b-a)
	elif s=='*':
		stack.append(b*a)

		

S = list(input().split())

stack = []
for s in S:
	if s in ['+', '-', '*']:
		calc(stack, s)
	else:
		stack.append(int(s))

print(stack[0])
