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
operands = ["+","-","*"]
symbols = raw_input().split()
ans = 0
i = 0
while True:
    if len(symbols) == 1:
        break
    if symbols[i] in operands:
        a = int(symbols.pop(i-2))
        b = int(symbols.pop(i-2))
        o = symbols.pop(i-2)
        if o == "*":
            symbols.insert(i-2,a*b)
        elif o == "+":
            symbols.insert(i-2,a+b)
        elif o == "-":
            symbols.insert(i-2,a-b)
        else:
            "This operand is invalid."
            break
        i-=1
    else:
        i+=1
print symbols[0]