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
stack = []

for s in input().split():
  if s in '+-*':
    res = 0
    b = stack.pop(-1)
    a = stack.pop(-1)
  
    if s == '+': 
      res = a + b
    elif s == '-':
      res = a - b
    elif s == '*':
      res = a * b
  
    stack.append(res)
  else:
    stack.append(int(s))

print(stack[0])

