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 = []

def func(A):
    for i in range(len(A)):
        if (A[i] in "+-*"):
            x = S.pop()
            y = S.pop()
            S.append(str(eval(y + A[i] + x)))
        else:
            S.append(A[i])
    return S[0]

A = list(input().split(" "))
print (func(A))
