// Java version with (slow) Scanner
import java.util.*;

public class LinesPerHour_Godmar
{
    public static void main(String []av) {
        var sc = new Scanner(System.in);
        int n = sc.nextInt();
        int lph = sc.nextInt();
        int [] loc = new int[n];
        for (int i = 0; i < n; i++)
            loc[i] = sc.nextInt();
        Arrays.sort(loc);
        int total_loc = 0;
        int answer = 0;

        for (var l : loc) {
            total_loc += l;
            if (total_loc > 5 * lph)
                break;
            answer++;
        }
        System.out.println(answer);
    }
}