import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.PriorityQueue;
import java.math.BigInteger;
    
public class Main{

static final InputStream in=System.in;
static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE/2;
static final long LINF=Long.MAX_VALUE/2;
static int N;
static int[] count;
static int MAX_L=5000000;
static boolean[] canUse=new boolean[10];

public static void main(String[] args) throws IOException{
InputReader ir=new InputReader(in);
N=ir.nextInt();
for(int i=0;i<N;i++) canUse[ir.nextInt()]=true;
boolean[] isPrime=sieveOfEratosthenes();
int[] p=new int[MAX_L/2];

int t=0;
for(int i=0;i<=MAX_L;i++) if(isPrime[i]) p[t++]=i;
int l,r,ans,cnt;
l=r=0;
ans=-1;
while(true){
if(check(p[r])) r++;
else{
if(l!=r&&test()){
int L=(r==t)?MAX_L:p[r]-1;
int K=(l==0)?1:p[l-1]+1;
ans=Math.max(ans,L-K);
}
if(r==t) break;
Arrays.fill(count,0);
r++;
l=r;
}
}
out.println(ans);
out.flush();
}

public static boolean check(int a){
while(a!=0){
int rem=a%10;
if(!canUse[rem]) return false;
count[rem]++;
a/=10;
}
return true;
}

public static boolean test(){
for(int i=0;i<10;i++) if((count[i]==0&&canUse[i])||(count[i]>0&&!canUse[i])) return false;
return true;
}

public static boolean[] sieveOfEratosthenes(){
boolean[] res=new boolean[MAX_L+1];
Arrays.fill(res,true);
res[0]=res[1]=false;
for(int i=2;i<=Math.sqrt(MAX_L);i++){
if(res[i]) for(int j=i+i;j<=MAX_L;j+=i) res[j]=false;
}
return res;
}

static class InputReader {
private InputStream in;
private byte[] buffer=new byte[1024];
private int curbuf;
private int lenbuf;

public InputReader(InputStream in) {this.in=in;}
  
public int readByte() {
if(lenbuf==-1) throw new InputMismatchException();
if(curbuf>=lenbuf){
curbuf= 0;
try{
lenbuf=in.read(buffer);
}
catch (IOException e) {
throw new InputMismatchException();
}
if(lenbuf<=0)
return -1;
}
return buffer[curbuf++];
}

public boolean isSpaceChar(int c){return !(c>=33&&c<=126);}

private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;}

public String next() {
int b=skip();
StringBuilder sb=new StringBuilder();
while(!isSpaceChar(b)){
sb.appendCodePoint(b);
b=readByte();
}
return sb.toString();
}
 
public int nextInt() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
int res=0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public long nextLong() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
long res = 0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public int[] toIntArray(int n){
int[] a=new int[n];
for(int i=0;i<n;i++) a[i]=nextInt();
return a;
}
}
}