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
l=list(input().split())
l=l[::-1]
stack=[]
while len(l)>0:
  n=l.pop()
  if n in ["+","-","*"]:
    a=int(stack.pop())
    b=int(stack.pop())
    if n=="+":
      stack.append(a+b)
    elif n=="-":
      stack.append(b-a)
    else:
      stack.append(a*b)
  else:
    stack.append(n)
print(stack[-1])
