Program joculflip;
Var  f:text;
     n,m,i,j:integer;
     sum,x:longint;
Begin
        assign(f,'flip.in');
        reset(f);
        read(f,m,n);
        sum:=0;
        for i:=1 to m do begin
        readln(f);
                for j:=1 to n do begin
                read(f,x);
                if x>0 then sum:=sum+x;
                end;
        end;
        close(f);
        assign(f,'flip.out');
        rewrite(f);
        write(f,sum);
        close(f);
end.