package q0xx;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Q34 {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	static void solve()
	{
		int[] primes = sieveEratosthenesL(5000000);
		int[] pptn = new int[5000001];
		for(int i = 0;i < primes.length;i++){
			int x = primes[i];
			int lptn = 0;
			while(x > 0){
				lptn |= 1<<x%10;
				x /= 10;
			}
			pptn[primes[i]] = lptn;
		}
		
		int n = ni();
		int ptn = 0;
		for(int i = 0;i < n;i++){
			ptn |= 1<<ni();
		}
		
		int[] f = new int[10];
		int tail = 1;
		int maxlen = -1;
		outer:
		for(int head = 1;head <= 5000000;head++){
			for(int j = 0;j <= 9;j++){
				if(pptn[head]<<~j<0)f[j]++;
			}
			inner:
			while(true){
				for(int j = 0;j <= 9;j++){
					if(f[j] > 0 && ptn<<~j>=0){
						for(int k = 0;k <= 9;k++){
							if(pptn[tail]<<~k<0)f[k]--;
						}
						tail++;
						continue inner;
					}
				}
				break;
			}
			
			for(int j = 0;j <= 9;j++){
				if((f[j] > 0) != (ptn<<~j<0))continue outer;
			}
			maxlen = Math.max(maxlen, head-tail);
		}
		out.println(maxlen);
	}
	
	public static int[] sieveEratosthenesL(int n)
	{
		if(n <= 64){
			int[] primes = {2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61};
			for(int i = 0;i < primes.length;i++){
				if(n < primes[i]){
					return Arrays.copyOf(primes, i);
				}
			}
			return primes;
		}
		
		int u = n+64;
		double lu = Math.log(u);
		int[] ret = new int[(int)(u/lu+u/lu/lu*1.5)];
		ret[0] = 2;
		int pos = 1;
		
		long[] isnp = new long[(n+1)/64/2+1];
		int sup = (n+1)/64/2+1;
		
		int[] tprimes = {3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61};
		for(int tp : tprimes){
			ret[pos++] = tp;
			long[] ptn = new long[tp];
			for(int i = (tp-3)/2;i < tp<<6;i+=tp)ptn[i>>6] |= 1L<<i;
			for(int j = 0;j < sup;j += tp){
				for(int i = 0;i < tp && i+j < sup;i++){
					isnp[j+i] |= ptn[i];
				}
			}
		}
		
		// 3,5,7
		// 2x+3=n
		final int[] magic = {0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28, 62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11, 63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10, 51, 25, 36, 32,
	              60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12};
		int h = n/2;
		for(int i = 0;i < sup;i++){
			for(long j = ~isnp[i];j != 0;j &= j-1){
				int pp = i<<6|magic[(int)((j&-j)*0x022fdd63cc95386dL>>>58)];
				int p = 2*pp+3;
				if(p > n)break;
				ret[pos++] = p;
				if((long)p*p > n)continue;
				for(int q = (p*p-3)/2;q <= h;q += p)isnp[q>>6] |= 1L<<q;
			}
		}
		
		return Arrays.copyOf(ret, pos);
	}
	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private static char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}