fn main() {
    let addr = "3BMEXMnbEmo6vSn4GgHxSq6rhv54dWqAnk";
    // let addr = "bc1qtpdptcf4ngfkwq6dr36kqaeh2n5h00rx5unkgc";
    let char_n = if &addr[0..=3] == "bc1q" {
        3 as usize
    } else {
        1 as usize
    };
    println!("prefix: {:?}", addr[0..=char_n].to_owned());
    println!("char_1: {:?}", addr[char_n + 1..=char_n + 1].to_owned());
    println!("char_2: {:?}", addr[char_n + 2..=char_n + 2].to_owned());
    println!("char_3: {:?}", addr[char_n + 3..=char_n + 3].to_owned());
    println!("char_4: {:?}", addr[char_n + 4..=char_n + 4].to_owned());
    println!("char_5: {:?}", addr[char_n + 5..=char_n + 5].to_owned());
    println!("char_6: {:?}", addr[char_n + 6..].to_owned());
}