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
I = input().split()
a = []
for i in I:
    if i.isdigit():
        a.append(int(i))
    else:
        n = a.pop()
        m = a.pop()
        if i == "+":
            a.append(m+n)
        if i == "-":
            a.append(m-n)
        if i == "*":
            a.append(n * m)
print(a[0])

