program flip;
var v:array [1..100] of integer;
		f,g:text;
		i,j,n,m,x:integer;
		s:longint;
begin
	assign(f,'flip.in');
	assign(g,'flip.out');
	reset(f);
	rewrite(g);

	read(f,n);
	read(f,m);

	x:=1;
	for i:=1 to n do
	 for j:=1 to m do
		begin
			read(f,v[x]);
			x:= x+1;
		end;

	 s:=0;
	 for i:=1 to x do
		begin
			if v[i] > 0 then
				s:= s + v[i];
		end;

write(g,s);
close(f);
close(g);
end.