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
def stack(data):
    s = []
    for i in data:
        if i in "+-*":
            a2 = s.pop()
            a1 = s.pop()
            s.append(str(eval(a1 + i + a2)))
        else:
            s.append(i)
    print(s[0])

if "__main__" == __name__:
    data = input().split()
    stack(data)

