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
data = list(input().split(" "))
stack = []
for d in data:
    if d == '+':
        stack.append(stack.pop() + stack.pop())
    elif d == '-':
        stack.append(- stack.pop() + stack.pop())
    elif d == '*':
        stack.append(stack.pop() * stack.pop())
    else:
        stack.append(int(d))
print(stack[0])