using static System.Console;
 
public class Program {
	public static void Main() {
		int number;
		do {
			WriteLine("Enter a number between 1111 and 9999: ");
			number = int.Parse(ReadLine()); //isto dá erro se digitar algo errado, deveria usar TryParse()
		} while (number < 1111 || number > 9999);
		var texto = "";
		while (number > 0) {
			texto = number % 10 + "\n" + texto; //o uso de \n pode não ser o ideal sempre
			number /= 10;
		}
		WriteLine(texto);
	}
}
 
//https://pt.stackoverflow.com/q/220446/101

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

MTExMQ==

1111