#include <bits/stdc++.h>
using namespace std;

int main()
{
  int N, ai;
  cin >> N;
  map <int,int> A;
  for(int i=0;i<N;i++){
    cin >> ai;
    if(A.count(ai) > 0){ cout << "NO" << endl; return 0;}
    else A[ai] = 1;
  }
  cout << "YES" << endl;
}
#include <bits/stdc++.h>
using namespace std;
struct point{int x;int y;};
int i,j,k,count1=0,count2=0;

int main(){
    string s;
    cin>>s;
    for(i=0;i<s.length()-1;i++){
        if(s[i]=='A'&&s[i+1]=='C'){
            cout<<"Yes"<<endl;
            return 0;
        }
    }
    cout<<"No"<<endl;
}