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
n = list(map(str,input().split()))
stack = []
for i in n:
    if i.isnumeric():
        stack.append(i)
    else:
        x_1 = stack.pop()
        x_2 = stack.pop()
        tmp = eval(x_2 + i + x_1)
        stack.append(str(tmp))
else:
    print(stack.pop())

