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
A = input().split()
S = []


for i in A:
    if i == '+' or i == '-' or i == '*':
        a = S.pop()
        b = S.pop()
        if i == '+': S.append(b+a)
        elif i == '-': S.append(b-a)
        else: S.append(b*a)
    else:
        x = int(i)
        S.append(x)
    #print(S)

print(S[0])
