program number;
var
  a:array[0..11,0..11]of integer;
  i,n,min,m,x:integer;
procedure ini;
var
  i,j:integer;
Begin
  assign(input,'number.in');
  assign(output,'number.out');
  reset(input); rewrite(output);
  readln(m,n);
  for  i:=1 to n do begin
    for j:=1 to m do  read(a[i,j]);
  end;
  min:=maxint;
End;
procedure ouo;
Begin
  if min=maxint then min:=-1;
  writeln(min);
  close(input);  close(output);
End;
procedure go(i,j,x:integer);
var
  k,l:integer;
Begin
  if (i<>n)or(j<>m) then begin
    for k:=1 to 2 do begin
      if (k=1)and(j<=m) then go(i,j+1,x+a[i,j+1])
      else begin
        if (i<=n)then begin
          k:=2;
          go(i+1,j,x+a[i+1,j]);
        end;
      end;
    end;
  end
  else if (x<min)and(x>0) then min:=x;
End;
Begin
  ini;
  x:=a[1,1];
  go(1,1,x);
  ouo;
 End.