#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 8;
int n;
string ss;
int num[26] = {0};
int flag = 0;
int main() {
  cin >> n;
  cin >> ss;
  if (n > 26 || n == 1)
    cout << "Yes";
  else {
    for (int i = 0; i < ss.size(); i++) {
      num[ss[i] - 'a']++;
      if (num[ss[i] - 'a'] >= 2) {
        flag = 1;
        break;
      }
    }
    if (flag)
      cout << "Yes";
    else
      cout << "No";
  }
  return 0;
}
