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
box = []
elem = input().split()
for i in elem:
    if i == '+' or i == '-' or i =='*':
        v = '{0} {1} {2}'.format(box[-2],i,box[-1])
        box.pop()
        box.pop()
        box.append(eval(v))
    else:
        box.append(i)
print (box[0])