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 = list(map(str, input().split()))
A = []
for x in X:
    if x.isnumeric():
        A.append(int(x))
    else:
        a = A.pop()
        b = A.pop()
        if x == '+':
            A.append(a+b)
        elif x == '-':
            A.append(b-a)
        else:
            A.append(a*b)
print(A[0])

