#include <bits/stdc++.h>
using namespace std;
char s[110], s1[6][10];
int n;
bool check(int i, int op) {
  int m = strlen(s1[op]);
  for (int j = 0; j < m; j++)
    if (s[i + j] != s1[op][j]) return 0;
  return 1;
}
int main() {
  scanf("%s", s + 1);
  n = strlen(s + 1);
  s1[1][0] = 'N';
  s1[1][1] = 'i';
  s1[1][2] = 'k';
  s1[1][3] = 'i';
  s1[1][4] = 't';
  s1[1][5] = 'a';
  s1[2][0] = 'D';
  s1[2][1] = 'a';
  s1[2][2] = 'n';
  s1[2][3] = 'i';
  s1[2][4] = 'l';
  s1[3][0] = 'S';
  s1[3][1] = 'l';
  s1[3][2] = 'a';
  s1[3][3] = 'v';
  s1[3][4] = 'a';
  s1[4][0] = 'O';
  s1[4][1] = 'l';
  s1[4][2] = 'y';
  s1[4][3] = 'a';
  s1[5][0] = 'A';
  s1[5][1] = 'n';
  s1[5][2] = 'n';
  int w = 0;
  for (int i = 1; i <= n; i++) {
    if (n - i + 1 >= 6) w += check(i, 1);
    if (n - i + 1 >= 5) w += check(i, 2) + check(i, 3);
    if (n - i + 1 >= 4) w += check(i, 4);
    if (n - i + 1 >= 3) w += check(i, 5);
  }
  if (w == 1)
    puts("YES");
  else
    puts("NO");
  return 0;
}
