use proconio::input; fn main() { input! { n: usize, } println!("{}", solve(n)); } fn solve(n: usize) -> usize { (1_usize..).find(|&exp| pow_mod(10, exp, n) == 1).unwrap() } /// Calculate the remainder of `exp` power of `base` divided by `m`. pub fn pow_mod(base: usize, exp: usize, m: usize) -> usize { let mut ret = 1 % m; let mut mul = base % m; let mut t = exp; while t != 0 { if t & 1 == 1 { ret = ret * mul % m; } mul = mul * mul % m; t >>= 1; } ret }