Problem: i want to write a letter in a combobox for finding the correct alternative (in a webpage)

Hi, Sorry but i need to know how can i use the UIPATH for this action.

In a webpage there a combobox with 100 alternatives. But the problem is i don´t have the complete alternative in a variable. So i need to write the first letter to find de correct alternative. Eg:

alternative 1: user A123
alternative 2: user A124
alternative 3: user A135
alternative 4: user B123

So i want to find two options: A123, A124 but i need to find just write in a combobox (A12 and the page show me the 2 correct alternatives).

Please your help.