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
s = raw_input()
l = s.split(' ')
stk = []

for i in l:
  if i in ['+','-','*','/']:
    b = stk.pop()
    a = stk.pop()
    if i == '+':
      c = a+b
      stk.append(c)
    elif i == '-':
      c = a-b
      stk.append(c)
    elif i == '*':
      c = a * b
      stk.append(c)
    elif i == '/':
      c = a / b
      stk.append(c)
  else:
    stk.append(int(i))
print stk[0]