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 operate(operand0, operand1, operator):
    if operator == "+":
        return str(int(operand0) + int(operand1))
    elif operator == "*":
        return str(int(operand0) * int(operand1))
    elif operator == "-":
        return str(int(operand0) - int(operand1))

if __name__ == "__main__":
    import sys
    expr = sys.stdin.readline().strip().split()
    stack = []
    for t in expr:
        if t.isdigit():
            stack.append(t)
        else:
            a = stack.pop()
            b = stack.pop()
            stack.append(operate(b, a, t))
    print stack.pop()