#![allow(unused_imports)]
//use itertools::{iproduct, Itertools};
use proconio::input;
use proconio::marker::*;
use std::collections::*;

fn main() {
    input! {
        n:usize,
        p:[Usize1;n],
    }

    let mut nexts = vec![None; n];
    let mut prevs = vec![None; n];
    for i in 0..n {
        if i != n - 1 {
            nexts[p[i]] = Some(p[i + 1]);
        }
        if i != 0 {
            prevs[p[i]] = Some(p[i - 1]);
        }
    }

    let mut rem = (0..n).collect::<BTreeSet<_>>();
    let mut ans = vec![];
    while !rem.is_empty() {
        let fst = *rem.first().unwrap();
        if let Some(nxt) = nexts[fst] {
            ans.push(fst);
            ans.push(nxt);
            match (prevs[fst], nexts[nxt]) {
                (Some(pre), Some(nnxt)) => {
                    nexts[pre] = Some(nnxt);
                    prevs[nnxt] = Some(pre);
                }
                (Some(pre), None) => {
                    nexts[pre] = None;
                }
                (None, Some(nnxt)) => {
                    prevs[nnxt] = None;
                }
                _ => (),
            }

            rem.remove(&fst);
            rem.remove(&nxt);
            continue;
        }

        let scn = *rem.iter().nth(1).unwrap();
        if let Some(nxt) = nexts[scn] {
            ans.push(scn);
            ans.push(nxt);

            match (prevs[scn], nexts[nxt]) {
                (Some(pre), Some(nnxt)) => {
                    nexts[pre] = Some(nnxt);
                    prevs[nnxt] = Some(pre);
                }
                (Some(pre), None) => {
                    nexts[pre] = None;
                }
                (None, Some(nnxt)) => {
                    prevs[nnxt] = None;
                }
                _ => (),
            }

            rem.remove(&scn);
            rem.remove(&nxt);
        }
    }

    for i in 0..n {
        print!("{} ", ans[i] + 1);
    }
    println!();
}