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
if __name__ == "__main__":
    stack =[]
    ope = {"+": lambda a, b: b + a, "-": lambda a, b: b - a, "*": lambda a, b: b * a}
    for x in input().split():
        if x in ope:
            stack.append(ope[x](stack.pop(),stack.pop()))
        else:
            stack.append(int(x))
    print(stack[-1])