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
inputs = input().split(" ")
stack = []

for str in inputs:
  if str.isdigit():
    stack.append(int(str))
  else:
    b = stack.pop()
    a = stack.pop()
    if str == '+':
      stack.append(a + b)
    elif str == '-':
      stack.append(a - b)
    elif str == '*':
      stack.append(a * b)

print(stack.pop())
