use std::collections::HashMap;

use proconio::input;

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

    let mut cnts0 = HashMap::new();
    let mut cnts1 = HashMap::new();
    let mut cnt0 = 0;
    let mut cnt1 = 0;
    cnts0.insert(a[0], 1);
    for i in 1..n {
        let cnt = cnts1.entry(a[i]).or_insert(0);
        if *cnt == 1 {
            cnt1 += 1;
        }

        *cnt += 1;
    }

    let mut ans = vec![];
    if cnt0 == 0 && cnt1 == 0 {
        ans.push(1);
    }
    for i in 1..n - 1 {
        let Some(cnt)=cnts1.get_mut(&a[i])else{
            return;
        };
        if *cnt == 2 {
            cnt1 -= 1;
        }
        *cnt += 1;

        let cnt = cnts0.entry(a[i]).or_insert(0);
        if *cnt == 1 {
            cnt0 += 1;
        }
        *cnt += 1;

        if cnt0 == 0 && cnt1 == 0 {
            ans.push(i + 1);
        }
    }

    println!("{}", ans.len());
    for i in ans {
        print!("{} ", i);
    }
    println!()
}