#include<stdio.h>

int main(){
    int N;
    scanf("%d",&n);
    int ids[N];
    int i,j;
    int found=0;
    
    for(i=0;i<N;i++){
        scanf*("%d",&ids[i]);
        
    }
    
    for (i=0;i<N;i++){
        for (j=i+1; j<N;j++){
            if (ids[i]==ids[j]){
                printf("%d",ids[i]);
                found=1;
                break;
            }
        }
    }
    if (!found){
        printf("No duplicates found");
        
    }
    return 0;
}