Help write in C please

3. You are to write a subroutine named "keypad4x4 integer" that will use the keypad to input multi-digit integers. (You may use any of the functions from kevpad4x4,h as building blocks) When called, the subroutine should read characters from the 4x4 keypad. If the characters are in the range O9,the new digit should be added to the number. If the first key pressed is"". thenum negative. If the key is pressed, it indicates the end of input and the resulting integer should be returned. If any other key is pressed, it should be ignored