import java.util.*;

public class Main {
	public static void main (String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int n = sc.nextInt();
    	int[][] dp = new int[n + 1][10];
    	Arrays.fill(dp[0], -1);
    	dp[0][0] = 0;
    	for (int i = 1; i <= n; i++) {
    	    int x = sc.nextInt() % 10;
    	    for (int j = 0; j < 10; j++) {
    	        dp[i][j] = dp[i - 1][j];
    	    }
    	    for (int j = 0; j < 10; j++) {
    	        if (dp[i - 1][j] >= 0) {
    	            dp[i][(j + x) % 10] = Math.max(dp[i][(j + x) % 10], dp[i - 1][j] + 1);
    	        }
    	    }
    	}
    	System.out.println(dp[n][0]);
	}
}