Var f,g:text;
    m,n,lk,i,j,s,stemp:longint;
Begin
assign (f,'flip.in');
assign (g,'flip.out');
reset(f);
rewrite (g);
Readln (f,n,m);
for i:=1 to n do
    begin
    for j:=1 to m do
    begin
    read (f,lk);
    stemp:=stemp+lk;
    end;
    readln (f);
    stemp:=abs(stemp);
    s:=s+stemp;
    stemp:=0;
    end;
Writeln (g,s);
close(f);
close(g);
End.