#include <stdio.h>

int  main(){
    int N, ids[100], dupes[100], dupecote = 0;
    int freq[2001] = {0};
    scanf("%d",&N);
    
    if (N < 1) {
        printf("Invalid inpute\n");
        return 0;
    }
    for (int i=0; i<N; i++) {
        scanf("%d",&ids[i]);
        int idx = ids[i] +1000;
        freq[idx]++;
        if (freq[idx] == 2) {
            dupes[dupecount++] = ids[i];
        }
    }
    if (dupecount == 0) {
        printf("No duplicates found\n");
    }else{
        for (int i=0; i < dupecount; i++) {
            printf("%d",dupes[1]);
            if (i < dupecount - 1) printf(" ");
        }
        printf("\n");
    }
    return 0;
}