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
S = input().split()
L = []
for s in S:
    try:
        f = int(s)
        L.append(s)
    except ValueError:
        p = L.pop()
        q = L.pop()
        L.append(eval(str(q) + s + str(p)))
print(L[0])
