Write a program that prompts the user to input a number of positive integer values which is terminated by an appropriate sentinel value (you can choose -1 as the sentinel value) and then prints out the largest value, the smallest value, the average value and the number of prime numbers that exist in the input. For example, if the user input:
3 1 8 9 2 7 -1
the output is:
The largest value = 9
The smallest value = 1
The average value = 5
The number of primes = 3