Write a program to calculate the average of all scores entered between 0 and 100. Use a sentinel-controlled loop variable to terminate the loop. After values are entered and the average calculated, test the average to determine whether an A,B,C,D or F should be recorded. The scoring rubric is as follows: A - 90 - 100; B - 80 - 89; C - 70 - 79; D - 60 - 69; F < 60.

This is for C#.