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()
sentence = s.split(" ")
stack = []

for factor in sentence:
	if factor == "+":
		b = stack.pop()
		a = stack.pop()
		c = a + b
		stack.append(c)
	elif factor == "-":
		b = stack.pop()
		a = stack.pop()
		c = a - b
		stack.append(c)
	elif factor == "*":
		b = stack.pop()
		a = stack.pop()
		c = a * b
		stack.append(c)
	else:
		stack.append(int(factor))
print stack[0]