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
import sys

for line in sys.stdin:
  items = line.strip().split()

stack = []

for item in items:
  if item == '+' or item == '-' or item == '*':
    x = stack.pop()
    y = stack.pop()
    exp = "%s %s %s" % (y, item, x)
    stack.append(eval(exp))
  else:
    stack.append(int(item))

print stack.pop()