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
l=list(input().split())  ##文字も数字も入る
stack=[]

for x in l: ##リストの長さ文だけ繰り返し
    if x in ['+','-','*']: ##←知らなかった判定方法
        t=str(stack.pop()) ##末尾取り出し
        r=str(stack.pop())
        c=r+x+t
        stack+=[int(eval(c))] ##eval:入力した式の入力

    else:
        stack+=[int(x)] ##[]の意味?>リストに追加

print(stack.pop())

