# Interpolation search algorithm
def interpolation_search(list, target_element, start, end):

    if start <= end and (target_element >= list[start] and target_element <= list[end]):
        mid_point = start + int((float(end - start) / (list[end] - list[start])) * (target_element - list[start]))

        if (list[mid_point] == target_element):
            return mid_point
        elif (list[mid_point] < target_element):
            return interpolation_search(list, target_element, mid_point + 1, end)
        else:
            return interpolation_search(list, target_element, start, mid_point - 1)

    # Return -1 if condition is not fulfilled
    return -1

# A sample of sorted number list
sorted_num_list = [1, 3, 10, 14, 18, 22, 49, 50, 66, 88, 120]

# Display the sorted number list
print("List of numbers: {0}".format(sorted_num_list))

# Get user input
while True:
    try:
        num = int(input("Enter a number to get the position: "))
        break
    except ValueError:
        print("Please enter a number only.\n")

# Performs interpolation search of
# the number specified by the user.
pos = interpolation_search(sorted_num_list, int(num), 0, len(sorted_num_list) - 1)

# Display the result
print("The number {0} is found at position {1}.".format(num, pos) if pos != -1 else "The number you're looking for is not in the list.")