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