public static void Main()
Console.Write("Enter your marks: ");
int marks = Convert.ToInt32(Console.ReadLine());
if (marks >= 94 && marks <= 100)
else if (marks >= 87 && marks <= 93)
else if (marks >= 80 && marks <= 86)
else if (marks >= 77 && marks <= 79)
else if (marks >= 73 && marks <= 76)
else if (marks >= 70 && marks <= 72)
else if (marks >= 67 && marks <= 69)
else if (marks >= 63 && marks <= 66)
else if (marks >= 60 && marks <= 62)
else if (marks >= 50 && marks <= 59)
else if (marks >= 0 && marks <= 49)
Console.WriteLine("Invalid input. Make sure that marks should be between 0 and 100.");
Console.WriteLine("Your grade is: " + grade);