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
arr = list(input().split())
stack = []

for i in arr:
    if i == "+":
        stack.append(stack.pop()+stack.pop())
    elif i == "-":
        stack.append(-(stack.pop()-stack.pop()))
    elif i =="*":
        stack.append(stack.pop()*stack.pop())
    else:
        stack.append(int(i))
print(stack[-1])


