#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e14;
const long long N = 3e6 + 1;
const long long mod = 1e9 + 7;
const long double eps = 1E-7;
long long n, m, q, a[N], cnt;
string s;
int main() {
  ios_base::sync_with_stdio(0);
  ;
  cin >> s;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == 'D' and s[i + 1] == 'a' and s[i + 2] == 'n' and
        s[i + 3] == 'i' and s[i + 4] == 'l')
      cnt++, i += 4;
    if (s[i] == 'O' and s[i + 1] == 'l' and s[i + 2] == 'y' and s[i + 3] == 'a')
      cnt++, i += 3;
    if (s[i] == 'S' and s[i + 1] == 'l' and s[i + 2] == 'a' and
        s[i + 3] == 'v' and s[i + 4] == 'a')
      cnt++, i += 4;
    if (s[i] == 'A' and s[i + 1] == 'n' and s[i + 2] == 'n') cnt++, i += 2;
    if (s[i] == 'N' and s[i + 1] == 'i' and s[i + 2] == 'k' and
        s[i + 3] == 'i' and s[i + 4] == 't' and s[i + 5] == 'a')
      cnt++, i += 5;
  }
  if (cnt == 1) return cout << "YES", 0;
  cout << "NO";
}
