struct UnionFind {
    n: usize,
    parents: Vec<usize>,
}

impl UnionFind {
    fn new(n: usize) -> Self {
        UnionFind {
            n: n,
            parents: (0..n).collect(),
        }
    }

    fn equiv(&mut self, a: usize, b: usize) -> bool {
        self.find(a) == self.find(b)
    }
    
    fn unite(&mut self, a: usize, b: usize) {
        if self.equiv(a, b) { return; }
        let (a, b) = (a.min(b), a.max(b));
        let x = self.parents[a];
        let y = self.parents[b];
        self.parents[y] = self.parents[x];
    }

    fn find(&mut self, a: usize) -> usize {
        if self.parents[a] == a { return a; }
        let p = self.find(self.parents[a]);
        self.parents[a] = p;
        p
    }
}

fn dfs(cur: usize, prev: usize, goal: usize, paths: &Vec<Vec<(usize, usize)>>, used: &mut Vec<usize>) -> bool {
    if cur == goal {
        return true;
    }
    for &(v, bidx) in paths[cur].iter() {
        if v == prev { continue; }
        used.push(bidx);
        if dfs(v, cur, goal, paths, used) {
            return true;
        }
        used.pop();
    }
    false
}

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();
    let mut paths = vec![vec![]; n];
    let mut uf = UnionFind::new(n);
    let mut start = 0usize;
    let mut end = 0usize;
    let mut bridge = 0usize;
    for i in 0..n {
        let mut temp = String::new();
        std::io::stdin().read_line(&mut temp).ok();
        let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
        let u = temp[0]-1;
        let v = temp[1]-1;
        if uf.find(u) == uf.find(v) {
            start = u;
            end = v;
            bridge = i;
        } else {
            paths[u].push((v, i));
            paths[v].push((u, i));
            uf.unite(u, v);
        }
    }

    let mut used = vec![];
    dfs(start, start, end, &paths, &mut used);
    used.push(bridge);
    used.sort();
    println!("{}", used.len());
    println!("{}", used.iter().map(|v| (v+1).to_string()).collect::<Vec<_>>().join(" "));
}