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
formula = input().split()
operand = ['+', '-', '*', '/']
stuck = []

for c in formula:
    if c in operand:
        b = str(stuck.pop())
        a = str(stuck.pop())
        stuck.append(eval(''.join([a, c, b])))
    else:
        stuck.append(c)

print(stuck.pop())

