#include<stdio.h>
int main()
{
    int N;
    scanf("%d", &N);
    if (N<1)
    {
        printf("Invalid input");
        return 0;
    }
    int ids[100];
    int i,j;
    intfound=0;
    for(i=0;i<N;i++)
    {
        scanf("%d", &ids[i]);
    }
    for(i=0;i<N;i++)
    {
        for(j=i+1;j<N;j++)
        {
            if(ids[i]==ids[j])
            {
                pprintf("%d",ids[i]);
                found=1;
                break;
            }
        }
    }
    if(!found)
    {
        printf("No duplicates found");
    }
    return 0;
}