use proconio::{fastout, input, marker::Bytes};

#[fastout]
fn main() {
    input! {
        s: Bytes,
    }

    println!("{}", output(solve(s)))
}

fn solve(s: Vec<u8>) -> Vec<u8> {
    let mut ans = vec![s[0]];
    s.windows(2).for_each(|s| {
        if s[0] != s[1] {
            ans.push(s[1]);
        }
    });
    ans
}

fn output(ans: Vec<u8>) -> String {
    String::from_utf8(ans).unwrap()
}