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 = list(input().split())
s = []
for p in l:
    if p == '+':
        s.append(s.pop() + s.pop())
    elif p == '-':
        s.append(-(s.pop() - s.pop()))
    elif p == '*':
        s.append(s.pop() * s.pop())
    else:
        s.append(int(p))

print(s.pop())

