program energie;
var g,w,e,c,i,min:integer;
    f,r:text;
begin
assign(f,'energii.in');
reset(f);
assign(r,'energii.out');
rewrite(r);
read(f,g);
read(f,w);
min:=10000;
  for i:=1 to g do
  begin
  read(f,e,c);
        if (e>=w) and (c<=min) then min:=c;
  end;
if min=10000 then write(r,-1)
             else write(r,min);
close(f);close(r);
end.