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
rpn = map(str, raw_input().split())
stack = []

for i in rpn:
    if i.isdigit():
        stack.append(i)
    else:
        n1 = int( stack.pop() )
        n2 = int( stack.pop() )

    if   i == '+':
        stack.append( str(n2+n1) )
    elif i == '-':
        stack.append( str(n2-n1) )
    elif i == '*':
        stack.append( str(n2*n1) )

print stack[0]