#include<bits/stdc++.h>
using namespace std;
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(int i=0;i<(n);++i)
#define RANGE(i, a, b) for(int i=(a);i<(b);++i)
#define RREP(i, n) for(int i=(n)-1;i>= 0;--i)

#define endl '\n'
#define pb push_back
#define eb emplace_back
#define pque priority_queue
#define umap unordered_map
#define uset unordered_set
#define BIG 2000000000
#define VERYBIG 1000000000000000ll
#define dcout cout<<fixed<<setprecision(20)
#define Accepted_MAGIC cin.tie(0);ios::sync_with_stdio(false)

// typedef long long ll;
using Real = long double;
#define int long long

const long long dx[]={1,0,-1,0,1,1,-1,-1}, dy[]={0,-1,0,1,1,-1,1,-1};
const long long MOD = 1e9+7;
constexpr Real eps = 1e-9, pi = acos(-1);

template<typename T> inline T GCD(T a,T b){T c;while(b!=0){c=a%b;a=b;b=c;}return a;}
template<typename T> inline T LCM(T a,T b){T c=GCD(a,b);a/=c;return a*b;}
template<typename T> inline T nCr(T a,T b){T i,r=1;for(i=1;i<=b;i++){r*=(a+1-i);r/=i;}return r;}
template<typename T> inline T nHr(T a,T b){return nCr(a+b-1,b);}
template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}

typedef pair<int, int> INTP;
typedef vector<int> INTV;
struct edge2 {int to, cost;};
struct edge3 {int from, to, cost;};

int N;
vector<string> ans;

void dfs(int dep, string s){
  if(dep == N-1){
    ans.eb(s);
    return;
  }
  char c = s.back();
  for(char nx = 'a'; nx <= c+1; nx++){
    dfs(dep+1, s+nx);
  }
}

signed main(void){
  Accepted_MAGIC;
  
  cin >> N;
  dfs(0, "a");
  sort(ALL(ans));
  for(auto ele : ans){
    cout << ele << endl;
  }
}