title: Find A Fixed Point In A Given Array
signature: findAFixedPointInAGivenArray :: [Integer] -> Integer -> Integer
  findAFixedPointInAGivenArray arr n = 
source_py: def find_a_fixed_point_in_a_given_array(arr, n):
      for i in range(n):
          if (arr[i] is i):
              return i
      return (- 1)
source_cpp: int find_a_fixed_point_in_a_given_array(vector<int> arr, int n) {
    int i;
    for ( i = 0;
    i < n;
    i ++ ) {
      if ( arr [ i ] == i ) return i;
    }
    return - 1;
  }