//using System;
int[] times = {800, 1200, 1600, 2000};
int diff = 0;

/* Format and display medicine times */
void display_times(int[] times){ 
    foreach (int val in times) {
        string time = val.ToString();
        int len = time.Length;
        if (len >= 3) {
            time = time.Insert(len - 2, ":");
        }
        else if (len == 2) {
            time = time.Insert(0, "0:");
        } else {
            time = time.Insert(0, "0:0");
        }
        Console.Write($"{time} ");
    }
    Console.WriteLine();
}

void adjust_times(int diff){
    // Adjust the times by adding the difference,
    // keeping the value within 24 hours
    for (int i = 0; i < times.Length; i++) {
        times[i] = ((times[i] + diff)) % 2400;
    }
}

Console.WriteLine("Enter current GMT");
int current_GMT = Convert.ToInt32(Console.ReadLine());

Console.WriteLine("Current Medicine Schedule:");
display_times(times);

Console.WriteLine("Enter new GMT");
int new_GMT = Convert.ToInt32(Console.ReadLine());

if (Math.Abs(new_GMT) > 12 || Math.Abs(current_GMT) > 12) {
    Console.WriteLine("Invalid GMT");
} else if (new_GMT <= 0 && current_GMT <= 0 || new_GMT >= 0 && current_GMT >= 0)  {
    diff = 100 * (Math.Abs(new_GMT) - Math.Abs(current_GMT));
    adjust_times(diff);
} else {
    diff = 100 * (Math.Abs(new_GMT) + Math.Abs(current_GMT));
    adjust_times(diff);
}

Console.WriteLine("New Medicine Schedule:");
display_times(times);