#include <bits/stdc++.h>
using namespace std;
int main() {
  char s[1000];
  cin >> s;
  int size = strlen(s);
  int find1 = 0, find2 = 0, find3 = 0, find4 = 0, find5 = 0;
  for (int i = 0; i < size; i++) {
    if (size - i + 1 >= 5) {
      if (s[i] == 'D' && s[i + 1] == 'a' && s[i + 2] == 'n' &&
          s[i + 3] == 'i' && s[i + 4] == 'l')
        find1++;
    }
  }
  for (int i = 0; i < size; i++) {
    if (size - i + 1 >= 4) {
      if (s[i] == 'O' && s[i + 1] == 'l' && s[i + 2] == 'y' && s[i + 3] == 'a')
        find1++;
    }
  }
  for (int i = 0; i < size; i++) {
    if (size - i + 1 >= 5) {
      if (s[i] == 'S' && s[i + 1] == 'l' && s[i + 2] == 'a' &&
          s[i + 3] == 'v' && s[i + 4] == 'a')
        find1++;
    }
  }
  for (int i = 0; i < size; i++) {
    if (size - i + 1 >= 3) {
      if (s[i] == 'A' && s[i + 1] == 'n' && s[i + 2] == 'n') find1++;
    }
  }
  for (int i = 0; i < size; i++) {
    if (size - i + 1 >= 6) {
      if (s[i] == 'N' && s[i + 1] == 'i' && s[i + 2] == 'k' &&
          s[i + 3] == 'i' && s[i + 4] == 't' && s[i + 5] == 'a')
        find1++;
    }
  }
  if (find1 == 1)
    cout << "YES" << endl;
  else
    cout << "NO" << endl;
}
