#include<stdio.h>
int main() {
    int N;
    scanf("%d",&N);
    
    if (N < 1)
    {
        printf("Invalid input\n");
        return 0;
    }
    int ids[100];
    int freq[2001] = {0};
    int duplicates[2001] = {0};
    int dupcount= 0;
    
    for (int i = 0; i < N; i++) 
    {
        scanf("%d", &ids[i]);
        int index = ids[i] + 1000;
        freq[index]++;
    }
    for(int i = 0; i < N ; i++)
    {
        int index = ids[i] + 1000;
        if (freq[index] > 1)
        {
            int alreadyAdded = 0;
            for (int j =0; j < dupcount; j++)
            {
                if(duplicates[j] == ids[i])
                {
                    alreadyAdded = 1;
                    break;
                }
            }
        }
    }
        if (!alreadyAdded) {
                duplicates[dupcount++] = ids[1];
            }
    
    
        if(dupcount == 0 )
        {
            printf("No duplicates found \n");
        }
        else
        {
            for (int i =0; i < dupcount; i++)
            {
                printf("%d", duplicates[i]);
                if(i != dupcount- 1)
                printf(" ");
            }
            printf("\n");
            }
            return 0;
        }