This homework is due on 3/31/14

In this homework, you will read in a series of grades, store them in a
dynamic array, compute their average and then report the letter grade
result of the average. Grades can have decimal places. The number of
grades will change each time the program is run (thus requiring the
dynamic array). 



Be sure to create a dynamic array appropriately to receive credit.

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Sample Execution:
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How many grades would you like to enter? 5
Enter grade #1: 50
Enter grade #2: 55
Enter grade #3: 50.7
Enter grade #4: 99
Enter grade #5: 100
Your average is 70.94.
Your average is a C.
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The input above is:
5 50 55 50.7 99 100


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You should run sample executions based on the following inputs:
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1 70

3 10 20 30

5 50 55 50.7 99 100

5 90 80 70 60 50 40

2 0 0