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():
    e = raw_input().split()
    t = list()

    for i in e:
        if i == '+': t.append(t.pop() + t.pop())
        elif i == '-': t.append(-(t.pop()) + t.pop())
        elif i == '*': t.append(t.pop() * t.pop())
        else: t.append(int(i))

    print(t.pop())
main()