#include <bits/stdc++.h>
using namespace std;
long long power(long long x, long long y, long long md) {
  long long res = 1;
  x %= md;
  while (y > 0) {
    if (y & 1) res = (res * x) % md;
    x = (x * x) % md;
    y = y >> 1;
  }
  return res % md;
}
int main() {
  long long n;
  cin >> n;
  if (n == 1) {
    cout << "Yes";
    return 0;
  }
  string second;
  cin >> second;
  std::vector<long long> a(26, 0);
  for (long long i = 0; i < second.length(); ++i) {
    a[second[i] - 'a']++;
  }
  bool flag = false;
  for (long long i = 0; i < 26; ++i) {
    if (a[i] >= 2) {
      flag = true;
      break;
    }
  }
  if (flag) {
    cout << "Yes";
  } else {
    cout << "No";
  }
}
