program number;
var
  m,n,i,j,max:longint;
  table:array[1..30,1..30]of longint;
procedure find(x,y,data:longint);
begin
  data:=data+table[x,y];
  if (x=m)and(y=n) then begin
    if max<0 then begin
      if data>0 then max:=data;
    end
    else if (data>0)and(data<max) then max:=data;
  end
  else begin
    if x<m then find(x+1,y,data);
    if y<n then find(x,y+1,data);
  end;
end;
begin
  assign(input,'number.in');
  assign(output,'number.out');
  reset(input);
  rewrite(output);
  readln(m,n);
  for i:=1 to m do
  begin
    for j:=1 to n do
      read(table[i,j]);
    readln;
  end;
  max:=-1;
  find(1,1,0);
  writeln(max);
  close(input);
  close(output);
end.