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
my_stack = []
for my_str in input().split():
  if my_str in "+-*":
    b = my_stack.pop()
    a = my_stack.pop()
    my_stack.append(str(eval(a+my_str+b)))
  else:
    my_stack.append(my_str)
    
print(my_stack.pop())
