import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class ScoreCalculator {
    public static void main(String[] args) {
        int sum = 0;
        int count = 0;
        
        try (BufferedReader br = new BufferedReader(new FileReader("scores.txt"))) {
            String line;
            while ((line = br.readLine()) != null) {
                try {
                    sum += Integer.parseInt(line);
                    count++;
                } catch (NumberFormatException e) {
                    System.err.println("Invalid number format: " + line);
                }
            }
        } catch (IOException e) {
            System.err.println("Error reading file: " + e.getMessage());
        }
        
        if (count > 0) {
            double average = (double) sum / count;
            System.out.println("Average score: " + average);
        } else {
            System.out.println("No valid scores found.");
        }
    }
}