#include <iostream>#include <stdio.h>#include <stdlib.h>#include <string.h>using namespace std;#define maxl 500char st[maxl];int find(char *st){ if (st[0] <= 'z' && st[0] >= 'p') return 1; if (st[0] == 'N') { int x = find(st + 1); if (x == -1) return x; return 1 + x; } if (st[0] == 'I' || st[0] == 'D' || st[0] == 'E' || st[0] == 'C') { int x = find(st + 1); if (x == -1) return x; int y = find(st + 1 + x); if (y == -1) return x; return 1 + x + y; } return -1;}int main(){ while (scanf("%s", st) == 1) { if (find(st) == (signed int)strlen(st)) printf("YESn"); else printf("NOn"); } return 0;}
