use proconio::input;

fn main() {
    input!{
        s: String,
    };

    let mut result = 0;
    let mut white_segment;

    let first = s.chars().next().unwrap();
    if first == 'W' {
        white_segment = true;
    } else {
        white_segment = false;
    }

    for c in s.chars() {
        match c {
            'W' => if !white_segment {
                white_segment = true;
                result += 1;
            },
            'B' => if white_segment {
                result += 1;
                white_segment = false;
            },
            _ => (),
        }
    }

    println!("{}", result);
}