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
data = raw_input().split()
#figure = [chr(i) for i in range(ord('0'), ord('9')+1)]

stack = []

for i in range(len(data)):
	if data[i] == "+":
		stack[-2] = stack[-2] + stack[-1]
		del stack[-1]
		#print stack
	elif data[i] == "-":
		stack[-2] = stack[-2] - stack[-1]
		del stack[-1]
		#print stack
	elif data[i] == "*":
		stack[-2] = stack[-2] * stack[-1]
		del stack[-1]
		#print stack
	else:
		stack.append(int(data[i]))
		#print stack

print stack[0]