#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  string s;
  cin >> s;
  map<char, bool> f;
  for (int i = 0; i < n; i++) {
    if (f[s[i]]) {
      printf("Yes\n");
      return 0;
    }
    f[s[i]] = 1;
  }
  if (n == 1) {
    printf("Yes\n");
    return 0;
  }
  printf("No\n");
  return 0;
}
