pub fn answer(s : &str) -> u32 {
    let grid : Vec<Vec<char>> = s.split("\n")
        .map(|s| s.chars().collect())
        .collect();
    
    let rows : i32 = grid.len().try_into().unwrap();
    let cols : i32 = grid[0].len().try_into().unwrap();
    let mut total : u32 = 0;

    for y in 0..rows {
        for x in 0..cols {
            if grid[y as usize][x as usize] == 'X' {
                total = total + inspect_location(&grid, x, y, rows, cols)
            }
        }
    };

    total
}

fn inspect_location(grid : &Vec<Vec<char>>, x : i32, y : i32, rows : i32, cols : i32) -> u32 {
    let mut total = 0;

    for dx in -1..=1 {
        for dy in -1..=1 {
            if dx == 0 && dy == 0 {
                continue;
            }

            let (s_x, s_y) = ( x + 3 * dx, y + 3 * dy );

            if s_x < 0 || s_x >= rows || s_y < 0 || s_y >= cols {
                continue;
            }

            let m = grid[(y + 1 * dy) as usize][(x + 1 * dx) as usize];
            let a = grid[(y + 2 * dy) as usize][(x + 2 * dx) as usize];
            let s = grid[(y + 3 * dy) as usize][(x + 3 * dx) as usize];

            if m == 'M' && a == 'A'  && s == 'S' {
                total = total + 1;
            }
        }
    };

    total
}