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

l=input().split()

num=[]
for x in l:
    if x in ['+','-','*']:
        z,y=str(num.pop()),str(num.pop())
        y+=x+z
        num.append(int(eval(y)))
    else:
        num.append(int(x))


print(num.pop())

