program t2(input,output);
var
data:array[1..200,1..200]of longint;
i,j,n,m,x:integer;   max:longint;
 procedure ss(a,b:integer);
  var
   x,y,i,j:integer;   temp:longint;
   function check(a,b,i,j:integer):boolean;
    var
    o,ii,jj:longint;
    begin
    check:=false;
    o:=0; temp:=0;
    for ii:= a to i do
     for jj:= b to j do
      begin
       inc(o,data[ii,jj]);
      inc(temp);
      end;
     if o>0 then check:=true;



    end;
  begin

    for i:=a to n do
     for j:=b to m do
     if (check(a,b,i,j))and(temp>max) then max:=temp;
  end;
begin
assign(input,'long.in');
reset(input);
assign(output,'long.out');
rewrite(output);
readln(n,m);
fillchar(data,sizeof(data),0);
for i:= 1 to n do
 for j:= 1 to m do
     read(data[i,j]);
close(input); max:=0;
for i:= 1 to n do
for j:= 1 to m do
 ss(i,j);
writeln(max);
close(output);


end.