program energie;
var w,i,g,cmin,e,c:integer;
    f,r:text;
begin
assign(f,'energii.in');
reset(f);
assign(r,'energii.out');
rewrite(r);
read(f,g);
read(f,w);
cmin:=5001;
 for i:=1 to g do
    begin
    read(f,e,c);
        if (e>=w)and(c<=cmin) then cmin:=c;
    end;
if cmin<>5001 then write(r,cmin)
else write(r,-1);
close(f);close(r);
end.