use std::io::Read;

fn calc(k: u32, a: &[u32]) -> u32 {
    if k == 0 {
        return if a[0] & 1 != *a.last().unwrap() & 1 {1} else {0};
    }
    if (a[0] >> k) & 1 == (*a.last().unwrap() >> k) & 1 {
        return calc(k - 1, a);
    }
    let mut m = 0;
    while (a[m] >> k) & 1 == 0 {
        m += 1;
    }
    (1 << k) + std::cmp::min(calc(k - 1, &a[0..m]), calc(k - 1, &a[m..]))
}

fn run() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let n: usize = it.next().unwrap().parse().unwrap();
    let mut a: Vec<u32> = (0..n).map(|_| it.next().unwrap().parse().unwrap()).collect();
    a.sort();
    let ans = calc(29, &a);
    println!("{}", ans);
}

fn main() {
    run();
}