import java.util.*;
public class main{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        int n=scan.nextInt(),i,j,m=0,l=0,p=0;
        int[] arr=new int[n];
        if(n<0)
        {
            System.out.println("Invalid input");
        }
        else
        {
            for(i=0;i<n;i++)
            {
            arr[i]=scan.nextInt();
            if(m<0){System.out.println("Invalid input");p++;}
            else{a[i]=m;}
            i++;
            }
            for(i=0;i<n;i++)
            {
                for(j=i+1;j<n;j++)
                {
                    if(arr[i]==arr[j])
                    {
                        System.out.println(arr[i]);
                    }
                }
            }
        }
        
        if(l==0 && p==0)
        {
            System.out.println("No duplicates found");
        }
    }
}