macro_rules! read_line_to_tuple {
    ( $( $t:ty ),* ) => {{
        let mut input = String::new();
        std::io::stdin().read_line(&mut input).unwrap();
        let mut iter = input.split_whitespace();
        ( $( iter.next().unwrap().parse::<$t>().unwrap() ),* )
    }};
}

macro_rules! read_line_to_collection {
    ( $t:ty ) => {{
        let mut input = String::new();
        std::io::stdin().read_line(&mut input).unwrap();
        let iter = input.split_whitespace();
        iter.map(|x| x.parse().unwrap()).collect::<$t>()
    }};
}

use std::cmp::max;

fn main() {
    let _n = read_line_to_tuple!(usize);
    let a = read_line_to_collection!(Vec<i32>);

    let mut old = vec![std::i32::MIN; 10];
    old[0] = 0;
    for x in a.iter().map(|x| x % 10) {
        let mut new = old.clone();
        for i in 0..10 {
            let j = (i + x as usize) % 10;
            new[j] = max(new[j], old[i] + 1);
        }
        old = new;
    }
    println!("{}", old[0]);
}