#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
template <typename T>
using V = vector<T>;
template <typename T>
using VV = vector<V<T>>;
template <typename T>
using VVV = vector<VV<T>>;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n;
  cin >> n;
  string s;
  cin >> s;
  vi cnt(300);
  if (n == 1) {
    puts("Yes");
    return 0;
  }
  for (char c : s) {
    cnt[c]++;
  }
  for (int i = 'a'; i <= 'z'; i++) {
    if (cnt[i] > 1) {
      puts("Yes");
      return 0;
    }
  }
  puts("No");
  return 0;
}
