use std::io::Read; fn main() { let mut s = String::new(); std::io::stdin().read_to_string(&mut s).ok(); let mut v: Vec = s.split_whitespace().flat_map(str::parse).collect(); let m = v.pop().unwrap() as usize; let a = v[1..].iter().sum::() / v[0]; let g = (v[1..].iter().map(|x| (x - a).powi(2)).sum::() / v[0]).sqrt(); println!( "{}", (50. + if g == 0. { 0. } else { 10. * (v[m] - a) / g }).floor() ) }