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
s = []
F = {
    '+': lambda: s.append(s.pop() + s.pop()),
    '-': lambda: s.append(-s.pop() + s.pop()),
    '*': lambda: s.append(s.pop() * s.pop())
}

for op in input().split():
    if op in F:
        F[op]()
    else:
        s.append(int(op))

print(s.pop())