#include <bits/stdc++.h>
using uint = unsigned int;
inline uint rd() {
  static uint _;
  return scanf(" %u", &_), _;
}
unsigned char s[27];
uint cnt[26];
int main() {
  const uint n = rd();
  if (26 < n) return puts("Yes"), 0;
  scanf("\n");
  fread(s + 1, 1, n, stdin);
  for (uint i = 1; i <= n; ++i)
    if (++cnt[s[i] - 'a'] > 1) return puts("Yes"), 0;
  return puts(cnt[s[1] - 'a'] == n ? "Yes" : "No"), 0;
}
