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

int main(){
  ll n;
  cin>>n;
  string s;
  cin>>s;
  for(ll i=0;i<n;i++){
    for(ll j=i+1;j<n;j++){
      if(s[i]==s[j]){
        cout<<"Yes"<<endl;
        exit(0);
      }
    }
  }
  cout<<"No"<<endl;
}