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
def f(exp):
    from operator import add, mul
    ops = {"+": add, "-": lambda a, b:b - a, "*": mul}
    stack = []
    def g(s):
        if s in ops:
            stack.append(ops[s](stack.pop(), stack.pop()))
        else:
            stack.append(int(s))
    map(g, exp.split())
    return stack[-1]
print f(raw_input())