1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define FORD(i,a,b) for(int i=(b)-1;i>=(a);--i)
#define REP(i,n) FOR(i,0,n)
#define REPD(i,n) FORD(i,0,n)
#define VAR(v,w) __typeof(w) v=(w)
#define FORE(it,c) for(VAR(it,(c).begin());it!=(c).end();++it)
#define PB push_back
#define ALL(c) (c).begin(),(c).end()
#define SIZE(c) ((int)(c).size())
#define MP make_pair
#define FT first
#define SD second
#define CLEAR(a) memset((a), 0, sizeof(a))
#define INT(x) int x; scanf("%d", &x)
#define LLG(x) LL x; scanf("%lld", &x)
#define STR(n,x) char x[n]; scanf("%s", x)
#define LINE(n,x) char x[n]; gets(x)

typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<VI> VVI;
typedef vector<PII> VII;
typedef vector<double> VD;
typedef vector<LD> VLD;
typedef vector<LL> VLL;
typedef vector<bool> VB;

int main() {
	INT(n);
	LLG(k);
	char last = '~';
	do {
		--k;
		LL x = (1LL << min(n, 63)) - 1;
		LL m = k / x;
		if (last == '~' && m > 2) {
			printf("NIE\n");
			return 0;
		}
		char c = 'a' + m;
		if (c >= last) ++c;
		putchar(c);
		last = c;
		--n;
		k %= x;
	} while (k);
	putchar('\n');
}