#include<stdio.h>
int main(){
    int N;
    scanf("%d",&N);
    if (N < 1){
        printf("Invalid input\n");
        return 0;
    }
    int ids[N];
    int frequency[2001]= {0};
    int duplicates_found= 0;
    for(int i=0; i < N; i++){
        scanf("%d",&ids[i]);
        frequency[ids[i]+ 1000]++;
    }
    printf("Duplicate:");
    int first_duplicates =1;
    for (int i=0; i < N; i++){
        if (frequency[ids[i]] + 1000 > 1){
            if (first_duplicates){
                printf("%d", ids[i]);
                first_duplicates = 0;
            }else{
                printf("%d",ids[i]);
            }
            duplicates_found =1;
            frequency[ids[i] + 1000] = 0;
        }
    
        if (duplicates_found){
            printf("No duplicates found");
        }
        printf("\n");
        
        return 0;