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
ope = {"+": lambda a, b: a + b, "-": lambda a, b: b - a, "*": lambda a, b: a * b, "/": lambda a, b: a / b}
stack =[]

for i in input().split():
    if i in ope:
        stack.append(ope[i](stack.pop(),stack.pop()))
    else:
        stack.append(int(i))

print(stack[0])