#![allow(unused_imports)]
use {std::cmp::*, std::collections::*, std::io::Write, std::ops::*};

#[allow(unused_macros)]
macro_rules !dbg {($($e :expr ) ,*) =>{#[cfg (debug_assertions ) ] $({let (e ,mut err ) =(stringify !($e ) ,std ::io ::stderr () ) ;writeln !(err ,"{} = {:?}" ,e ,$e ) .unwrap () } ) *} ;}
#[allow(unused_macros)]
macro_rules !min {($a :expr $(,) *) =>{{$a } } ;($a :expr ,$b :expr $(,) *) =>{{std ::cmp ::min ($a ,$b ) } } ;($a :expr ,$($rest :expr ) ,+$(,) *) =>{{std ::cmp ::min ($a ,min !($($rest ) ,+) ) } } ;}
#[allow(unused_macros)]
macro_rules !chmin {($base :expr ,$($cmps :expr ) ,+$(,) *) =>{{let cmp_min =min !($($cmps ) ,+) ;if $base >cmp_min {$base =cmp_min ;true } else {false } } } ;}
#[allow(unused_macros)]
macro_rules !max {($a :expr $(,) *) =>{{$a } } ;($a :expr ,$b :expr $(,) *) =>{{std ::cmp ::max ($a ,$b ) } } ;($a :expr ,$($rest :expr ) ,+$(,) *) =>{{std ::cmp ::max ($a ,max !($($rest ) ,+) ) } } ;}
#[allow(unused_macros)]
macro_rules !chmax {($base :expr ,$($cmps :expr ) ,+$(,) *) =>{{let cmp_max =max !($($cmps ) ,+) ;if $base <cmp_max {$base =cmp_max ;true } else {false } } } ;}

#[allow(dead_code)]
mod scanner {
    use std;
    use std::io::Read;
    use std::str::FromStr;
    use std::str::SplitWhitespace;
    pub struct Scanner<'a> {
        it: SplitWhitespace<'a>,
    }
    impl<'a> Scanner<'a> {
        pub fn new(s: &'a String) -> Scanner<'a> {
            Scanner {
                it: s.split_whitespace(),
            }
        }
        pub fn next<T: FromStr>(&mut self) -> T {
            match self.it.next().unwrap().parse::<T>() {
                Ok(v) => v,
                _ => panic!("Scanner error"),
            }
        }
        pub fn next_chars(&mut self) -> Vec<char> {
            self.next::<String>().chars().collect()
        }
        pub fn next_vec<T: FromStr>(&mut self, len: usize) -> Vec<T> {
            (0..len).map(|_| self.next()).collect()
        }
    }
    pub fn read_string() -> String {
        let mut s = String::new();
        std::io::stdin().read_to_string(&mut s).unwrap();
        s
    }
}

fn main() {
    let sc = scanner::read_string();
    let mut sc = scanner::Scanner::new(&sc);
    let out = std::io::stdout();
    let mut out = std::io::BufWriter::new(out.lock());

    let n: usize = sc.next();
    let mut map = std::collections::BTreeMap::<(usize, usize), usize>::new();
    let mut to = vec![vec![]; n];
    for i in 0..n {
        let a = sc.next::<usize>() - 1;
        let b = sc.next::<usize>() - 1;
        to[a].push(b);
        to[b].push(a);
        map.insert((a, b), i);
        map.insert((b, a), i);
    }

    let mut stack = vec![];
    let mut node = vec![];
    let mut set = std::collections::BTreeSet::<usize>::new();
    dfs(0, 0, &to, &mut set, &mut stack, &mut node);
    let mut ans = vec![];
    for a in node.windows(2) {
        ans.push(map.get(&(a[0], a[1])).unwrap());
    }
    ans.push(map.get(&(node[0], node[node.len() - 1])).unwrap());
    writeln!(out, "{}", ans.len()).unwrap();
    for i in 0..ans.len() {
        if i != 0 {
            write!(out, " ").unwrap();
        }
        write!(out, "{}", ans[i] + 1).unwrap();
    }
    writeln!(out, "").unwrap();
}

fn dfs(
    u: usize,
    p: usize,
    to: &Vec<Vec<usize>>,
    set: &mut BTreeSet<usize>,
    stack: &mut Vec<usize>,
    ans: &mut Vec<usize>,
) -> bool {
    stack.push(u);
    set.insert(u);
    for &v in to[u].iter() {
        if v == p {
            continue;
        }
        if set.contains(&v) {
            while let Some(x) = stack.pop() {
                ans.push(x);
                if x == v {
                    break;
                }
            }
            return true;
        }
        if dfs(v, u, to, set, stack, ans) {
            return true;
        }
    }
    stack.pop();
    set.remove(&u);
    false
}