Write in C and controller is AVR

2. Suppose a system uses a button to connect PB4 to ground and the microcontroller polls to see when this occurs. Write two lines of C code to properly configure this pin. That is, assign values to the two pertinent special-function registers. 3. Port C pins 0-3 are connected to buttons with external pull-down resistors, and pin 4 controls an LED in common-anode configuration. Pins 5, 6, and 7 of Port C are unused. Write a program that turns on the LED when any one of the four buttons is pressed and turns it off otherwise