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
import sys


Stack = []

def push(x):
    Stack.append(x)

def pop():
    Stack.pop(-1)


def cul(exp):
    for val in exp:
        if val in ["+", "-", "*"]:
            a = int(Stack[-2])
            b = int(Stack[-1])
            if val == "+":
                x = a + b
            elif val == "-":
                x = a - b
            elif val == "*":
                x = a * b
            for i in range(2):
                pop()
            push(x)
        else:
            push(val)

    return Stack[0]


if __name__ == "__main__":
    exp = sys.stdin.read().strip().split(" ")
    ans = cul(exp)
    print ans