Simple Addition

Let's define the next recursive function $F(n)$, where

Let's define the function $S(p,q)$ as follows:

In this problem you have to calculate $S(p,q)$ on given values of $p$ and $q$.

Input

Consists of multiple test cases. Each line contains two nonnegative integers $p$ and $q(p\le q)$. $p$ and $q$ will fit in $32$ bit signed integer. Input is terminated by a line with two negative integers. This line should not be processed.

Output

For each pair $p$ and $q$ print the value $S(p,q)$ on a single line.

Examples