Example: CountDigitThreeOccurrences in Java

// CountDigitThreeOccurrences
import java.util.Scanner;

// Main class containing the entry point of the program
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Get input 'n' from the user
        System.out.print("Enter a non-negative integer (n): ");
        int n = scanner.nextInt();

        // Step 2: Initialize total count for digit '3'
        int totalCountOfThrees = 0;

        // Step 3: Loop through each number from 0 to n
        for (int i = 0; i <= n; i++) {
            int currentNumber = i;
            // Step 4: Count '3's in the current number
            while (currentNumber > 0) {
                if (currentNumber % 10 == 3) {
                    totalCountOfThrees++;
                }
                currentNumber /= 10;
            }
            // Special case for number 0 if it contains '3' (not applicable here, but good practice)
            // For 0, the loop currentNumber > 0 won't run, so it correctly counts 0 '3's.
        }

        // Step 5: Print the total count
        System.out.println("Total occurrences of digit '3' from 0 to " + n + ": " + totalCountOfThrees);

        scanner.close();
    }
}