var a:array[1..17,1..17]of longint;
    n,m,i,j:1..17;
    s1:longint;
    f,q:text;
begin
 assign(f,'flip.in');
 reset(f);
 assign(q,'flip.out');
 rewrite(q);
 s1:=0;
 read(f,n,m);
 for i:=1 to n do
  for j:=1 to m do
   read(f,a[i,j]);
 for i:=1 to n do
  for j:=1 to m do
   if a[i,j]>0 then s1:=s1+a[i,j];
 write(q,s1);
 close(f);
 close(q);
end.