10分，求救pascal

var
 t,x,y:array[0..1001] of longint;
 n,m,ans,k1,k2,k,i,j:longint;
 function max(a,b:longint):longint;
 begin
  if a>b then exit(a)
  else exit(b);
 end;
begin
 read(n,m);
 for i:=1 to m do
  read(t[i],x[i],y[i]);
  x[0]:=x[1];
  y[0]:=x[1];
{ for i:=1 to n do}
  for j:=2 to m do
  begin
   k1:=x[j]-x[0];
   k2:=y[j]-y[0];
   k:=max(k1,k2);
   if k<=t[j]-t[j-1] then begin
                           inc(ans);
                           x[0]:=x[j];
                           y[0]:=y[j];
                          end;
  end;
 write(ans);
end.