The tasks of the topic Ref:

Modify React Element Input:

• Only natural numbers can be entered in the fields. All the rest characters shoulkd be ignored. Use regular expressions for this.
• When page is loaded, first input (operator field) are focused. Use ref for this.
• If the User enters 2 numbers in the operator field, the name of the corresponding mobile operator will appear and the cursor focus will move to the next input field (ref using). Mobile operators:
  • Kyivstar: 67, 68, 96, 97, 98
  • Vodafone: 50, 66, 95, 99
  • Lifecell: 63, 73, 93
  • 3mob: 91
  • People.net: 92
  • intertelecom: 89, 94
  • Unknown: other 2 digit numbers
• If the User entered 2 numbers in the operator field and 7 numbers in the phone field, then - will be replaced by ✔️ in .check-icon element.
• Modify only ./components/input/input.js.
• Use onInput event listenets for inputs.
• Save html structure of Input and do not delete data-testid attributes. They will be used for testing.

You can use functional component for the solution