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#include <cstdio>
#include <iostream>

#define DBG(X)

using namespace std;
char sout[1000001];

unsigned long long dp[1000001];

unsigned long long maxPot60()
{
  unsigned long long p = 1;
  int w = 1;
  while (w <= 60)
  {
    p *= 2;
    DBG(cout << w << " " << p << endl;)
    w++;
  }
  return p;
}

int main()
{
  int n;
  unsigned long long k;
  scanf("%d %llu", &n, &k);
  
  DBG(printf("%llu\n", maxPot60());
  printf("%d %llu\n", n, k);
  cout << maxPot60() << endl;)
  
  unsigned long long all = 0;
  unsigned long long pot = 1ULL;
  int wykl = 1;
  
  while (pot <= k && wykl < n)
  {
    pot *= 2ULL;
    pot++;
    wykl++;
  }
  pot *= 3ULL;
  
  if (pot < k)
  {
    printf("NIE\n");
    return 0;
  }
  
  dp[1] = 1ULL;
  
  for (int i = 2; i <= n; i++)
  {
    if (dp[i - 1] == maxPot60())
    {
      dp[i] = dp[i - 1];
    }
    else
    {
      dp[i] = dp[i - 1] * 2 + 1;
    }
  }
  
  
  int cnt = 0;
  char last = 'a';
  char tab1[4] = "baa";
  char tab2[4] = "ccb";
  
  DBG(cout << "dp " << dp[n] << endl;)
  
  if (dp[n] >= k)
  {
    last = 'a';
    //k -= dp[n];
    k--;
  }
  else if (2 * dp[n] >= k)
  {
    last = 'b';
    k -= dp[n];
    k--;
  }
  else
  {
    last = 'c';
    k -= 2 * dp[n];
    k--;
  }
  DBG(cout << "last " << last << " k = " << k << endl;)
  dp[0] = 0;
  sout[0] = last;
  if (k)
  for (int i = n - 1; i >= 1; i--)
  {
    if (dp[i] > k)
    {
      last = tab1[(last - 'a') % 3];
      sout[n - i] = last;
      k--;
    }
    else if (dp[i] == k)
    {
      last = tab1[(last - 'a') % 3];
      sout[n - i] = last;
      //k -= dp[i];
      //k--;
      //break;
    }
    else if (dp[i] < k)
    {
      last = tab2[(last - 'a') % 3];
      sout[n - i] = last;
      k -= dp[i];
      k--;
    }
    DBG(cout << "dp " << dp[i] << " last " << last << " k = " << k << endl;)
//    if (k==1) break;
    //else break;
    if (!k)
    {
      break;
    }
    
  }
  
  
  printf("%s\n", sout);
  return 0;
}