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
a = list(input().split())
l = []
for c in a:
    if c == '+':
        l.append(l.pop() + l.pop())
    elif c == '-':
        l.append((l.pop() - l.pop()) * -1)
    elif c == '*':
        l.append(l.pop() * l.pop())
    else:
        l.append(int(c))
print(l.pop())