int f(int x,int y);
int main()                        //????
{
	int x,y;
	cin >> x >> y ;
	cout << f( x, y) << endl;
	return 0;
}
int f(int x,int y)                //?????
{
	while(x!=y)                   //??x=y??x;?????????????????
	{
		if(x>y)
			x=x/2;
		else
			y=y/2;
		return f(x,y);
	}
	return x;                     //??????????
}
