r=x-p[x]?x=p[x],r:x
f='y|=a[i]==a[x+=i]&&(p[x=i,u=r]=r)==u'
p=({0..9999})
read w h
read -dx -aa
for((;x=i<w*h>y;~i%w&&f,x=w,f,++i)){ :;}
im
echo ${_[y]}possible