public static void Main()
int marksSum = int.Parse(Console.ReadLine());
marksSum += int.Parse(Console.ReadLine());
marksSum += int.Parse(Console.ReadLine());
marksSum += int.Parse(Console.ReadLine());
marksSum += int.Parse(Console.ReadLine());
double avg = Math.Round(marksSum / (double)5, 2);
if (5.50 <= avg && avg <= 6)
Console.WriteLine("A " + avg);
else if (4.50 <= avg && avg <= 5.49)
Console.WriteLine("B " + avg);
else if (3.50 <= avg && avg <= 4.49)
Console.WriteLine("C " + avg);
else if (3.00 <= avg && avg <= 3.49)
Console.WriteLine("D " + avg);
else if (2.00 <= avg && avg <= 2.99)
Console.WriteLine("F " + avg);