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 main():
    exp = [i for i in input().split()]
    stack = []

    for elem in exp:
        if elem.isdigit():
            stack.append(int(elem))
        else:
            n2, n1 = str(stack.pop()), str(stack.pop())
            stack.append(int(eval(n1 + elem + n2)))

    print(stack[0])

main()

