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())
s=[]
for l in L:
  s.append(l)
  if l in ['+','-','*']:
    op=s.pop()
    b=int(s.pop())
    a=int(s.pop())
    s.append(a+b) if op=='+' else s.append(a-b) if op=='-' else s.append(a*b)
print(s[0])
