import java.util.Arrays; import java.util.Scanner; /** * 第一题AC. */ public class Main { public static void main(String[] args){ Scanner in = new Scanner(System.in); while (in.hasNext()){ int n = in.nextInt(); int[] d = new int[n]; for (int i = 0; i < n; i++) { d[i] = in.nextInt(); } Arrays.sort(d); int l = 1, add = 0; for(int j=1;j<n;j++){ if(d[j]-d[j-1]>20){ if((j-l)%3!=0){ add+=(3-(j-l)%3); l=j; } } } if((n-l+1)%3!=0) add+=(3-(n-l+1)%3); System.out.println(add); } } }