<prompt> Kwa mfano, kuandika programu ya TypeScript ambayo inachukua nyuzi kama pembejeo na kurudisha herufi ya kwanza isiyo ya mara kwa mara katika nyuzi zilizopewa, programu inapaswa kupuuza nafasi na herufi zisizo za alfabeti, na kurudisha null ikiwa herufi zote zinarudiwa au ikiwa nyuzi ya pembejeo ni tupu, suluhisho linapaswa kuwa na ufanisi na bora katika suala la utata wa wakati.  <response>: Anyone who wants to use the word Input should use the word Input instead of the word Input or the word Input or the word Input or the word Input instead of the word Input or the word Input or the word Input instead of the word Input or the word Input instead of the word Input or the word Input instead of the word Input or the word Input instead of the word Input or the word Input Input instead of the word Input Input or the word Input instead of the word Input or the word Input in case of the word Input or the word Input in case of the word Input or the word Input in case of Input or the word Input Input in case of Input in case of Input in case of Input in case of Input in case of Input in case of 