#include<stdio.h>

int main(){
    int n,i,j,k, ids[100],dup=0
    Scanf("%d ", & n)
    if (n< 1){
        printf("Invalid Input");
        return 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]){
        for (k=0; k<i;k++)
        if(ids [k] == ids[i])break;
        if (k ==i){
            printf("%d",ids[i]);
            dup = 1;
            
        }
    }
    
    if(!dup) printf("No Duplicate Found");
    return 0; 
}