program jocul_Flip;
var
 n,m:byte;
 temp,s,countn,countm:longint;
 f,g:text;
begin
 assign(f,'flip.in');
 assign(g,'flip.out');
 reset(f);
 read(f,m);
 read(f,n);
 countm:=0;
 repeat
 countn:=0;
 countm:=countm+1;
 if countm<=m then
 repeat
 read(f,temp);
 countn:=countn+1;
 if countn>n then
  temp:=0;
 if temp>0 then
  s:=s+temp;
 until eoln(f);
 until (eof(f)) or (countm>m);
 close(f);
 rewrite(g);
 write(g,s);
 close(g);
end.