const
  jx:array[1..4]of longint=(-1,0,1,0);
  jy:array[1..4]of longint=(0,1,0,-1);

var
  n,m,i,j,ans:longint;
  a:array[0..100,0..100]of longint;
  ch,v:array[0..100,0..100]of boolean;

procedure go(x,y,k,s:longint);
var
  xx,yy,i:longint;
begin
  if s>ans then ans:=s;
  for i:=1 to 4 do
  begin
    xx:=x+jx[i];
    yy:=y+jy[i];
    if (ch[xx,yy])and(not v[xx,yy]) then
    begin
      v[xx,yy]:=true;
      if k=1 then
      begin
        if a[xx,yy]>a[x,y] then go(xx,yy,1,s+1)
        else if a[xx,yy]<a[x,y] then go(xx,yy,-1,s+1)
      end
      else begin
        if a[xx,yy]<a[x,y] then go(xx,yy,-1,s+1);
      end;
      v[xx,yy]:=false;
    end;
  end;
end;

begin
  assign(input,'hike.in'); reset(input);
  assign(output,'hike.out'); rewrite(output);
  readln(n,m);
  for i:=1 to n do
   for j:=1 to m do
   read(a[i,j]);

  for i:=1 to n do
   for j:=1 to m do
   ch[i,j]:=true;

  for i:=1 to n do
   for j:=1 to m do
   begin
     v[i,j]:=true;
     go(i,j,1,1);
     v[i,j]:=false;
   end;

  writeln(ans);
  close(input);
  close(output);
end.