F3 573 then TK 1075 at Istanbul
Riyadh → Istanbul → Varna
Timetable, Istanbul time
21:30F3 573 from Riyadh at the gate
21:00TK 1075 to Varna leaves the gate
23 h 30 apart on the timetable, overnight
TK 1075 leaves 23 h 30 after F3 573 arrives on the timetable: more than half a day, so not a connection we count.