fn main() {
    let mut nm = String::new();
    std::io::stdin().read_line(&mut nm).ok();
    let nm: Vec<usize> = nm.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nm[0];
    let m = nm[1];
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut paths = vec![vec![]; n];
    for _ in 0..m {
        let mut uv = String::new();
        std::io::stdin().read_line(&mut uv).ok();
        let uv: Vec<usize> = uv.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
        let u = uv[0]-1;
        let v = uv[1]-1;
        if a[u] < a[v] {
            paths[u].push(v);
        }
        if a[v] < a[u] {
            paths[v].push(u);
        }
    }
    let mut k = String::new();
    std::io::stdin().read_line(&mut k).ok();
    let k: usize = k.trim().parse().unwrap();
    let mut b = String::new();
    std::io::stdin().read_line(&mut b).ok();
    let b: Vec<usize> = b.trim().split_whitespace().map(|s| s.parse::<usize>().unwrap()-1).collect();

    let mut lamps = vec![0usize; n];
    for &v in b.iter() { lamps[v] = 1; }
    let mut a = (0..n).map(|i| (a[i], i)).collect::<Vec<_>>();
    a.sort();
    let mut result = vec![];
    for &(_, u) in a.iter() {
        if lamps[u] == 0 { continue; }
        result.push(u);
        lamps[u] = 0;
        for &v in paths[u].iter() {
            lamps[v] = 1 - lamps[v];
        }
    }
    if lamps.iter().sum::<usize>() == 0 {
        println!("{}", result.len());
        for &v in result.iter() {
            println!("{}", v+1);
        }
    } else {
        println!("-1");
    }
}