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
arr = [ i for i in input().split(" ")]

# 1 2 +
operands = ["+", "-", "*", "/"]

s = []

for i in arr:
  if i not in operands:
    s.append(i)
  
  if i in operands:
    val2 = s.pop()
    val1 = s.pop()

    s.append(eval("{0} {1} {2}".format(val1, i, val2)))

print(s[-1])
