#include <bits/stdc++.h>
using namespace std;
const int MOD = 998244353;
inline long long min(long long x, long long y) { return x > y ? y : x; }
inline long long max(long long x, long long y) { return x < y ? y : x; }
inline long long gcd(long long x, long long y) {
  return y == 0 ? x : gcd(y, x % y);
}
int main() {
  ios::sync_with_stdio(false);
  int n;
  string s;
  while (cin >> n >> s) {
    if (n == 1) {
      cout << "Yes\n";
      continue;
    }
    int a[30] = {0};
    for (int i = 0; i <= s.length() - 1; ++i) a[s[i] - 'a']++;
    int k = 0;
    for (int i = 0; i <= 28; ++i)
      if (a[i] > 1) {
        cout << "Yes\n";
        k = 1;
        break;
      }
    if (!k) cout << "No\n";
  }
  return 0;
}
