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