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
a = list(input().split())

stack = []

for ch in a:
    if ch in ['+', '-', '*']:
        b = int(stack.pop())
        a = int(stack.pop())

        if ch == '+':   stack.append(a+b)
        elif ch == '-': stack.append(a-b)
        else:           stack.append(a*b)
    else:   stack.append(ch)

print(stack[0])
