(h,w),*m=$<.map{|l|l.split.map(&:to_i)+[0]}+[[0]*100]
(h*w).times{|i|
  *a=i
  (
    v,*a=a
#    m[y=v%h][v/h]==$c&&(m[y][v/h]=-1;((y<1?[]:[-1])+[1,-h,h]).count{|w|a<<w+=v;m[w%h][w/h]<0}>1&&($><<:possible;exit))
    m[y=v%h][v/h]==$c&&(m[y][v/h]=-1;((y<1?[]:[-1])+[1,-h,h]).count{|w|w+=v;t=m[w%h][w/h];t==$c&&a<<w;t<0}>1&&($><<:possible;exit))
  )while a[0]if 0<$c=m[i%h][i/h]
  m.map{|n|n.map!{|t|t<0?0:t}}
}
$><<:impossible