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 = []
for t in input().split():
	try:
		v = int(t)
	except ValueError:
		a = s.pop()
		b = s.pop()
		if t == '+': v = b + a
		elif t == '-': v = b - a
		elif t == '*': v = b * a
	s.append(v)
print(s.pop())
