// yukicoder: No.233 めぐるはめぐる (3)
// bal4u 2019.8.25

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef long long ll;

//// 高速入力
#if 1
#define gc() getchar_unlocked()
#define pc(c) putchar_unlocked(c)
#else
#define gc() getchar()
#define pc(c) putchar(c)
#endif

int in() {   // 非負整数の入力
	int n = 0, c = gc();
	do n = 10 * n + (c & 0xf); while ((c = gc()) >= '0');
	return n;
}

char c2d[128];
char d2c[] = "_aeiubgmnr";

ll ins() {   // 文字列の特殊入力
	ll n = 0; int c = gc();
	do n = 10 * n + c2d[c]; while ((c = gc()) > ' ');
	return n;
}

void outs(char *s) { while (*s) pc(*s++); pc('\n'); }

char s[15];
void pr(ll x) {
	int i;
	for (i = 10; i >= 0; i--) s[i] = d2c[x % 10], x /= 10;
	outs(s);
}

// 数値のハッシュ関数
#define HASHSIZ  1296007
ll hash[HASHSIZ+5], *hashend = hash+HASHSIZ;

int lookup(ll n) {
	ll *p = hash + (int)(n % HASHSIZ);
	while (*p) {
		if (*p == n) return 0;
		if (++p == hashend) p = hash;
	}
	return 1;
}

void insert(ll n) {
	ll *p = hash + (int)(n % HASHSIZ);
	while (*p) {
		if (*p == n) return;
		if (++p == hashend) p = hash;
	}
	*p = n;
}

//// 本問題関連

// char d2c[] = "_aeiubgmnr";
char code[11] = { 1,1,2,3,4,4,5,6,7,8,9 };
char f[11];

void rec(int id, ll x, int bo) {
	int i, j; ll y;
	if (id == 11) {
		if (lookup(x)) { pr(x); exit(0); }
		return;
	}
	x *= 10;
	for (i = 6; i < 11; i++) if (f[i]) {
		f[i] = 0, y = 10*(x + code[i]);
		for (j = 0; j < 6; j++) if (f[j]) {
			f[j] = 0, rec(id+2, y + code[j], bo), f[j] = 1;
		}
		f[i] = 1;
	}
	if (!bo) for (i = 0; i < 6; i++) if (f[i])
		f[i] = 0, rec(id+1, x + code[i], 1), f[i] = 1;
}
		
int main()
{
	int i, N;

	for (i = 0; d2c[i]; i++) c2d[d2c[i]] = i;
	N = in();
	if (N == 129600) { outs("NO"); return 0; }
	while (N--) insert(ins());
	
	memset(f, 1, sizeof(f));
	rec(0, 0, 0);
	outs("NO");
	return 0;
}