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 main():
    l = input().split(' ')

    s = []

    for el in l:
        if el in ["+", "-", "*"]:
            a = s.pop(-1)
            b = s.pop(-1)
            s.append(eval(str(b) + el + str(a)))
        else:
            s.append(int(el))

    print(s[0])

main()
