#include<stdio.h>
int main(){
    int N;
    scanf("%d",&N);
    if (N<1){
        printf("invalid input ");
        return 0;
    }
    int ids[100];
    int dubplicates[100];
    int duCount=0;
    for (int i=0 ; i<N;i++){
        scanf ("%d",&ids[i]);
    }
    for(int i=0;i<N;i++){
        for (int j=i+1;j<N;j++){
            if (ids[i]==ids[j]){
                int alraedyfound =0;
                for (int k=0;k < dupCount;k++){
                    if (duplicates[k]==ids[i]){
                        alreadyfound=1
                        break;
                    }
                }
                if (!alreadyfound){
                    duplicates[ducCount++]=ids[i];
                }
            }
        }
    }
    if (dupCount==0){
        printf("no duplicates fonud\n");
        }else{
            for(inti=0;i<dupCount;++){
                printf("%d",duplicates[i]);
            }
        }
        return 0;
}