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use std::str::FromStr;


#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, RustcDecodable, RustcEncodable)]
pub struct Point {
    pub x: usize,
    pub y: usize,
}

impl FromStr for Point {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if s.len() != 2 {
            return Err(());
        }
        let mut chars = s.chars();
        let letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
        let numbers = ['1', '2', '3', '4', '5', '6', '7', '8'];
        let grid_x = chars.next().unwrap_or('0');
        let grid_y = chars.next().unwrap_or('0');
        let x = match letters.iter().position(|c| *c == grid_x) {
            Some(num) => num,
            None => return Err(()),
        };
        let y = match numbers.iter().position(|c| *c == grid_y) {
            Some(num) => num,
            None => return Err(()),
        };
        Ok(Point { x: x, y: y })
    }
}