#![allow(unused_imports)]

use std::io::{self, BufRead};
use std::str::FromStr;
use std::collections::*;
use std::cmp::*;

#[allow(dead_code)]
struct Parser<'a> {
    tokens: &'a mut Iterator<Item = String>,
}
#[allow(dead_code)]
impl<'a> Parser<'a> {
    fn new(i: &'a mut Iterator<Item = String>) -> Self {
        Parser {tokens: i}
    }
    fn take<T: FromStr>(&mut self) -> T {
        match self.tokens.next().expect("empty iterator").parse() {
            Ok(x) => x,
            Err(_) => panic!()
        }
    }

    fn take_some<T: FromStr>(&mut self, n: usize) -> Vec<T> {
        self.tokens.take(n).map(|s| match s.parse() { Ok(x) => x, Err(_) => panic!() } ).collect()
    }
}

//sieve[k] is true if k is a prime
//[0, n)
#[allow(dead_code)]
fn sieve_of_eratosthenes(n: u64) -> Vec<bool> {
    let mut v = vec![true; n as usize];
    v[0] = false;
    v[1] = false;
    for i in 2..n {
        if !v[i as usize] {
            continue;
        }
        let mut j = 2*i;
        while j < n {
            v[j as usize] = false;
            j += i;
        }
    }
    v
}

//[l, u)の素数
#[allow(dead_code)]
fn primes_in(l: u64, u: u64) -> Vec<u64> {
    sieve_of_eratosthenes(u).into_iter().zip(0..u).filter(|&x| x.0).map(|x| x.1).filter(|x| *x >= l).collect()
}

#[allow(dead_code)]
fn vec_2d<T>(n: usize, m: usize, t: T) -> Vec<Vec<T>> where T: Clone {
    let mut u = Vec::new();
    let mut v = Vec::new();
    v.resize(m, t);
    u.resize(n, v);
    u
}

fn main() {
    let stdin = io::stdin();
    let mut tokens = stdin.lock().lines().filter_map(|x| x.ok()).flat_map(|x| x.split_whitespace().map(|s| s.to_owned()).collect::<Vec<String>>());
    let mut parser = Parser::new(&mut tokens);

    let n: usize = parser.take();
    let a: Vec<usize> = parser.take_some(n);
    let mut b = [false; 10];
    for ai in a {
        b[ai] = true;
    }
    let b = b;

    let s = sieve_of_eratosthenes(5000001);
    let mut k = 1;
    let mut l = 1;
    let mut c = [false; 10];
    let mut ans = 0;
    while k <= 5000000 {
        if (0..10).all(|x| b[x] || !c[x]) {
            if s[k] {
                let mut k_ = k;
                while k_ > 0 {
                    c[k_%10] = true;
                    k_ /= 10;
                }
            }
            if (0..10).all(|x| b[x] == c[x]) {
                ans = max(ans, k-l);
            }
            k += 1;
        } else {
            l = k;
            for i in 0..10 {
                c[i] = false;
            }
        }
    }
    if ans == 0 {
        println!("{}", -1);
    } else {
        println!("{}", ans);
    }
}