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
x = raw_input().split()
s = []
for e in x:
    try:
        s.append(int(e))
    except:
        b = s.pop()
        a = s.pop()
        if e == '+':
            s.append(a+b)
        if e == '-':
            s.append(a-b)
        if e == '*':
            s.append(a*b)
print s.pop()