fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    let mut dp = vec![vec![-1; 10]; n+1];
    dp[0][0] = 0;
    for i in 0..n {
        for j in 0..10 {
            if dp[i][j] < 0 { continue; }
            dp[i+1][j] = dp[i+1][j].max(dp[i][j]);
            let idx = (j+a[i]) % 10;
            dp[i+1][idx] = dp[i+1][idx].max(dp[i][j]+1);
        }
    }
    println!("{}", dp[n][0]);
}