#include <bits/stdc++.h>
using namespace std;
long long ar[200010];
void solve() {
  long long a, b, c = 0, i, j, t, k, lie, m, n, o, x, y, z;
  long long p = 0, sm = 0, cnt = 0;
  scanf("%lld", &n);
  string s;
  cin >> s;
  if (n == 1) {
    printf("Yes\n");
    return;
  }
  for (i = 0; i < n; i++) ar[s[i] - 'a']++;
  for (i = 0; i < 26; i++) {
    if (ar[i] > 1) {
      printf("Yes\n");
      return;
    }
  }
  printf("No\n");
}
int main() {
  solve();
  return 0;
}
