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