#include <bits/stdc++.h>
using namespace std;
int n, i, r, a[256];
char x;
int main() {
  for (cin >> n; i < n; i++) {
    cin >> x;
    (a[x] > 0 ? r = 1 : 0);
    a[x]++;
  }
  cout << (r == 1 || n == 1 ? "Yes" : "No");
}
