#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 322;
const long long LINF = 2e18 + 228;
const int MAXN = 1e5 + 228;
const int MOD = 1e9 + 7;
const double eps = 1e-14;
string s;
int n, cnt;
void solve() {
  cin >> s;
  n = s.length();
  for (int i = 0; i < n; i++) {
    if (s[i] == 'D') {
      if (s[i + 1] == 'a' && s[i + 2] == 'n' && s[i + 3] == 'i' &&
          s[i + 4] == 'l') {
        cnt++;
      }
    }
    if (s[i] == 'O') {
      if (s[i + 1] == 'l' && s[i + 2] == 'y' && s[i + 3] == 'a') {
        cnt++;
      }
    }
    if (s[i] == 'S') {
      if (s[i + 1] == 'l' && s[i + 2] == 'a' && s[i + 3] == 'v' &&
          s[i + 4] == 'a') {
        cnt++;
      }
    }
    if (s[i] == 'A') {
      if (s[i + 1] == 'n' && s[i + 2] == 'n') {
        cnt++;
      }
    }
    if (s[i] == 'N') {
      if (s[i + 1] == 'i' && s[i + 2] == 'k' && s[i + 3] == 'i' &&
          s[i + 4] == 't' && s[i + 5] == 'a') {
        cnt++;
      }
    }
  }
  puts(cnt == 1 ? "YES" : "NO");
}
int main() {
  if (!1) {
    freopen(
        "474"
        ".in",
        "r", stdin);
    freopen(
        "474"
        ".out",
        "w", stdout);
  }
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int T = 1;
  while (T--) solve();
  return 0;
}
