Var f,g:Text;
    n,m,i,j,l,c,max,s,s1,s2:Longint;
    a:array[1..17,1..17] of Longint;


Begin

Assign(f,'flip.in');ReSet(f);
Assign(g,'flip.out');ReWrite(g);

ReadLn(f,n,m);

For i:=1 To n Do
    For j:=1 To m Do
        Read(f,a[i,j]);

If m<n Then Begin
   max:=0;

For i:=1 To m Do Begin
    s1:=0;
    s2:=0;
    For j:=1 To n Do Begin
        If a[j,i]<=0 Then s1:=s1+abs(a[j,i]);
        If a[j,i]>0 Then s2:=s2+a[j,i]*(-1);
        If s1+s2>max Then Begin
           max:=s1+s2;
           c:=i;
           End;
        End;
     End;

max:=0;

For i:=1 To m Do Begin
    s1:=0;
    s2:=0;
    For j:=1 To n Do Begin
        If a[i,j]<0 Then s1:=s1+abs(a[i,j]);
        If a[i,j]>0 Then s2:=s2+a[i,j]*(-1);
        If s1+s2>max Then Begin
           max:=s1+s2;
           l:=i;
        End;
    End;
End;
End
                Else Begin

max:=0;

For i:=1 To m Do Begin
    s1:=0;
    s2:=0;
    For j:=1 To n Do Begin
        If a[i,j]<0 Then s1:=s1+abs(a[i,j]);
        If a[i,j]>0 Then s2:=s2+a[i,j]*(-1);
        If s1+s2>max Then Begin
           max:=s1+s2;
           l:=i;
        End;
    End;
End;

max:=0;

For i:=1 To m Do Begin
    s1:=0;
    s2:=0;
    For j:=1 To n Do Begin
        If a[j,i]<=0 Then s1:=s1+abs(a[j,i]);
        If a[j,i]>0 Then s2:=s2+a[j,i]*(-1);
        If s1+s2>max Then Begin
           max:=s1+s2;
           c:=i;
           End;
        End;
     End;
End;
s:=0;

For i:=1 To n Do
    a[i,c]:=a[i,c]*(-1);

For i:=1 To m Do
    a[l,i]:=a[l,i]*(-1);

a[l,c]:=a[l,c]*(-1);

For i:=1 To n Do
    For j:=1 To m Do
        s:=s+a[i,j];

WriteLn(g,s);

Close(f);
Close(g);

End.