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
s = raw_input().split()

stack = []
for op in s:
	if op.isdigit():
		stack.append(op)
	else:
		b = int(stack.pop())
		a = int(stack.pop())
		ret = 0
		if op == "+":
			ret = a + b
		elif op == "-":
			ret = a - b
		elif op == "*":
			ret = a * b
		stack.append(str(ret))
print stack.pop()