#include<stdio.h>
int main(){
int n;
scanf("%d",&n);
if(n<1){
    printf("invalid input");
    return 0;
    
}
int ids[100];
int seen[100];
int duplicates[100];
int dupcount[100];
for(int i=0;i<n;i++){
    scanf("%d",&ids[i]);
}
for(int i=0;i<n;i++){
    int index=ids[i]+1000;
    if(seen[index]==1){
        int alreadyadd=0;
        for(int j=0; j< dupcount;j++){
            if(duplicates[j]==ids[i]){
                alreadyadd=1;
                break;
            }
        }
        if(!alreadyadd){
            duplicates[dupcount++]=ids[i];
        }
        else{
            seen[index]=1;
        }
        }
        if(dupcount=0){
            printf("No duplicates found\n");
        }
        else{
            for(int i=0;i<dupcount;i++){
                printf("%d",duplicates[i]);
                if(i<dupcount-1){
                    printf("");
                }
            }
            printf("\n")
        }
        
    }
    return 0;
}