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
class Stack:
    def __init__(self):
        self.values = []

    def push(self,v):
        self.values.append(v)

    def pop(self):
        if len(self.values) == 0:
            raise
        else:
            v = self.values[len(self.values)-1]
            del self.values[len(self.values)-1]
            return v

symbols = raw_input().split(' ')

stack = Stack()
for s in symbols:
    if not s in ['+', '-', '*']:
        stack.push(s)
    else:
        v1 = int(stack.pop())
        v2 = int(stack.pop())
        if s == '+':
            stack.push(v1+v2)
        elif s == '-':
            stack.push(v2-v1)
        elif s == '*':
            stack.push(v1*v2)

print stack.pop()