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
operand = []
for x in raw_input().split():
  if x.isdigit():
    operand.append(int(x))
  else:
    a1 = operand[len(operand)-1]
    operand.pop()
    a2 = operand[len(operand)-1]
    operand.pop()
    if  x == '+' :
      operand.append(a2 + a1)
    elif  x == '-':
      operand.append(a2 - a1)
    elif  x == '*':
      operand.append(a2 * a1)

print operand[0]