var f,g:text;i,n,m,q,a,s:longint;
begin
assign (f,'flip.in');
reset (f);
assign (g,'flip.out');
rewrite (g);
read (f,n,m);
repeat
for i:=1 to m do
begin
read (f,a);
q:=q+a;
end;
s:=s+abs(q);
until eof(f);
write (g,s);
close (g);
end.