I can't solve it! Please help me to solve the program :)

Write a recursive function that returns the nth Fibonacci number from the Fibonacci series.

Write a program in c to find the first digit of a number. example: 5326 - here the first digit is 5

arr[5] = { 1, 5, 5, 5, 2 } #delete all 5 in this array and print new array arr[2] = { 1, 2}