Exercise $3$

Write a program that asks the user for entering certain values, until he$/$she ends the program by entering $-1.$ When the user finishes entering the numbers, the program should display the number of entered numbers, their sum, average and the maximum.

Sample run:

Enter a value $(-1$ to end program$)$: $34$

Enter a value $(-1$ to end program$)$ : $56$

Enter a value $(-1$ to end program$)$: $77$

Enter a value $(-1$ to end program$)$: $-1$

You entered $3$ values

Their sum is: $167\mathrm{.}0$

Their average is $55\mathrm{.}67$

The highest number is: $77\mathrm{.}0$