use std::io::Read; fn get_word() -> String { let stdin = std::io::stdin(); let mut stdin=stdin.lock(); let mut u8b: [u8; 1] = [0]; loop { let mut buf: Vec = Vec::with_capacity(16); loop { let res = stdin.read(&mut u8b); if res.unwrap_or(0) == 0 || u8b[0] <= b' ' { break; } else { buf.push(u8b[0]); } } if buf.len() >= 1 { let ret = String::from_utf8(buf).unwrap(); return ret; } } } #[allow(dead_code)] fn get() -> T { get_word().parse().ok().unwrap() } /** * Returns the least index of elements that are modified, wrapped with Some. * If the entire array is reversed, it returns None instead. * v's elements must be pairwise distinct. */ fn next_permutation(v: &mut [T]) -> Option { let mut tail_dec: usize = 1; let n = v.len(); while tail_dec < n { if v[n - tail_dec - 1] > v[n - tail_dec] { tail_dec += 1; } else { break; } } // v[n - tail_dec .. n] is strictly decreasing if tail_dec < n { let x = n - tail_dec - 1; let mut y = n; { let pivot = &v[x]; for i in (n - tail_dec .. n).rev() { if v[i] > *pivot { y = i; break; } } assert!(y < n); } v.swap(x, y); } v[n - tail_dec .. n].reverse(); if tail_dec < n { Some(n - tail_dec - 1) } else { None } } fn main() { let k: usize = get(); let mut v: Vec = (1..9).collect(); let mut ans = 0; loop { let mut tmp = 0; for &w in &v { tmp = 10 * tmp + w; } if tmp % k == 0 { ans += 1; } if let None = next_permutation(&mut v) { break; } } println!("{}", ans); }