fn main() {
    println!("Hello, world!");
}

pub fn next_greatest_letter(letters: Vec<char>, target: char) -> char {
    let mut smallest: char = '~';
    let first = letters[0];

    for c in letters {
        if c > target && c < smallest {smallest = c;} 
    }
    if smallest == '~' {
        return first;
    }

    return smallest;
}