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
def ALDS1_3A():
  stk, RPexp = [], list(input().split())
  for v in RPexp:
      if v in '+-*':
          n2, n1 = stk.pop(), stk.pop()
          stk.append(str(eval(n1+v+n2)))
      else:
          stk.append(v)
  print(stk.pop())

if __name__ == '__main__':
    ALDS1_3A()