fn main() { let n: usize; inputm!(n); let a = input_vector::(); let mut dp = vec![vec![0; 10]; a.len() + 1]; dp[0][0] = 1; for i in 0..n { for j in 0..10 { dp[i + 1][j] = std::cmp::max(dp[i + 1][j], dp[i][j]); if dp[i][j] != 0 { dp[i + 1][(j + a[i]) % 10] = std::cmp::max(dp[i + 1][(j + a[i]) % 10], dp[i][j] + 1); } } } println!("{}", dp[n][0] - 1); } pub mod input { use std::io; const SPLIT_DELIMITER: char = ' '; #[macro_export] #[allow(unused_macros)] macro_rules! inputm { ( $($x:expr ),*) => { { let temp_str = input_line_str(); let mut split_result_iter = temp_str.split_whitespace(); $( let buf_split_result = split_result_iter.next(); let buf_split_result = buf_split_result.unwrap(); ($x) = buf_split_result.parse().unwrap(); )* } }; } pub fn input_line_str() -> String { let mut s = String::new(); io::stdin().read_line(&mut s).unwrap(); s.trim().to_string() } pub fn input_vector2d(line: usize) -> Vec> where T: std::str::FromStr, { let mut v: Vec> = Vec::new(); for _ in 0..line { let vec_line = input_vector(); v.push(vec_line); } v } #[allow(clippy::match_wild_err_arm)] pub fn input_vector() -> Vec where T: std::str::FromStr, { let mut v: Vec = Vec::new(); let s = input_line_str(); let split_result = s.split(SPLIT_DELIMITER); for z in split_result { let buf = match z.parse() { Ok(r) => r, Err(_) => panic!("Parse Error",), }; v.push(buf); } v } #[allow(clippy::match_wild_err_arm)] pub fn input_vector_row(n: usize) -> Vec where T: std::str::FromStr, { let mut v = Vec::with_capacity(n); for _ in 0..n { let buf = match input_line_str().parse() { Ok(r) => r, Err(_) => panic!("Parse Error",), }; v.push(buf); } v } pub trait ToCharVec { fn to_charvec(&self) -> Vec; } impl ToCharVec for String { fn to_charvec(&self) -> Vec { self.to_string().chars().collect::>() } } } use input::*;