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
array = input().split()
stack = []

while True:
    if len(array) == 0: break
    e = array.pop(0)
    if e.isdigit():
        stack.append(e)
    else:
        num1 = stack.pop()
        num2 = stack.pop()
        stack.append(str(eval(num2 + e + num1)))

print(stack[0])