#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
void no() {
  cout << "NO\n";
  exit(0);
}
int main() {
  int n;
  cin >> n;
  vector<int> arr(n);
  for (int i = 0; i < n; ++i) cin >> arr[i];
  sort(arr.begin(), arr.end());
  for (int i = n - 1; i >= 0; --i) {
    arr[i] -= arr[0];
    if (arr[i] >= n) no();
  }
  vector<int> cnt(n);
  for (int i = 0; i < n; ++i) cnt[arr[i]]++;
  int mx = arr[n - 1];
  for (int i = 1; i < mx; ++i) {
    if (cnt[i] < 2) no();
    cnt[i] -= 2;
  }
  cnt[0]--;
  cnt[mx]--;
  for (int i = 0; i <= mx; ++i) {
    while (cnt[i] > 0) {
      if (cnt[i + 1] == 0) no();
      cnt[i]--;
      cnt[i + 1]--;
    }
  }
  cout << "YES\n";
}
