    import java.util.*;
    public class Main{
        public static void main(String[] args){
            Scanner sc=new Scanner(System.in);
            int N=sc.nextInt();
            int A[];
            A=new int[N];
            for(int i=0;i<N;i++) A[i]=sc.nextInt();
            Arrays.sort(A);
            boolean ans=true;
            for(int i=0;i<N-1;i++) if(A[i]==A[i+1]) ans=false;
            System.out.println(ans?"YES":"NO");
        }
    }
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz