Turn Game 2

Yunho and Donghyeok are at an algorithm camp. When a problem will not come out, they take a break and play a game.

The game is made of turns, and each turn is won by one of the two players. Turns are numbered from 1, and the winner of turn $i$ earns $2i-1$ points.

The total number of turns is not fixed. Any number of turns is possible, including zero.

You are given two integers $x$ and $y$. Decide whether Yunho can end with $x$ points and Donghyeok with $y$ points. If that is possible, also find the smallest number of turns Yunho has to win.

The first line contains two integers $x$ and $y$. ($0 \le x, y \le 10^{12}$)

Print the smallest number of turns Yunho has to win. If scores $x$ and $y$ are impossible, print -1.