Write a program that allows users to enter a series of numbers and displays frequency of each number. Implement the following: 1. The user can enter a maximum of 20 numbers or enter-1 to end the series 2. Only numbers between 0 ... 9 is allowed (or - 1); if the user enters a number outside the valid input, inform the user and ask them to enter a valid number 3. Display the frequency of each number in the output. If the user input is 0,0,1,2,2,4,5,8,8,8,9,9, - 1 the output will be:

zero = one = two = three = four = five = six = seven = eight = nine = 0

while True:

number = int (input ("Enter a number: "))

if number = = - 1:

break

elif 0 < = number < = 9:

if number = = 0:

zero + = 1

elif number = = 1:

one + = 1

elif number = = 2:

two + = 1

elif number = = 3:

three + = 1

elif number = = 4:

four + = 1

elif number = = 5:

five + = 1

elif number = = 6:

six + = 1

elif number = = 7:

seven + = 1

elif number = = 8:

eight + = 1

elif number = = 9:

nine + = 1

else:

print ("Invalid input!")

print ("0 - > " + str (zero) + "," + " 1 - > " + str (one) + "," + " 2 - > " + str (two) + "," + " 3 - > " + str (three))

print ("4 - > " + str (four) + "," + " 5 - > " + str (five) + "," + " 6 - > " + str (six) + "," + " 7 - > " + str (seven))

print ("8 - > " + str (eight) + "," + " 9 - > " + str (nine))

Explanation:

Initialize the variables to hold the count for each digit

Initialize a while loop that iterates until a specified condition is reached

Inside the loop:

Get a number from the user and check

If the number is - 1, stop the loop

If it is between 0 to 9, increase corresponding count value by 1

If it is out of range, print an error message

When the loop is done, print each count variable