int unknownfunctionf1_nextpeace(int x,int y)
{
	return (15*y*x+3*x*x*x*x*y+x*x+y*y+7*x*x*x+9*x+x/2+y/2+7*y)%16;
}
int unknownfunctionF_nextpeace(int m,int k)
{
	int x=m%16,y=m/16;
	if(m<0||m>=256||k>=16||k<0) return 0;
	return 16*x+(y^unknownfunctionf1_nextpeace(x,k));
}
int RE(int m,int k1,int k2,int k3,int k4)
{
	if(m<0||m>=256||k1>=16||k1<0||k2>=16||k2<0||k3>=16||k3<0||k4>=16||k4<0) return -1;
	int z=unknownfunctionF_nextpeace(unknownfunctionF_nextpeace(unknownfunctionF_nextpeace(unknownfunctionF_nextpeace(m,k1),k2),k3),k4),x=z%16,y=z/16;
	return 16*x+y;
}