#include<bits/stdc++.h>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(0)
#define loop(i, a, b) for(lli i=a; i<b; i++)
#define loopb(i, a, b) for(lli i=a; i>=b; i--)
#define pb push_back
#define umap unordered_map
typedef long long int lli;
typedef pair<lli, lli> pii;
typedef vector<lli> vll;
typedef pair<lli, pii> ppi;
typedef tree<lli, null_type, less<lli>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
// use to avoid collision
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
// for pair in unordered_map
struct hash_pair {
    static uint64_t splitmix64(uint64_t x) {
    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
    }
    template <class T1, class T2>
    size_t operator()(const pair<T1, T2>& p) const{
        auto hash1 = hash<T1>{}(p.first);
        auto hash2 = hash<T2>{}(p.second);
        uint64_t x = hash1 ^ hash2;
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
lli M = 1e9 + 7;
lli power(lli x, lli y){
    lli res = 1;
    x = x%M ;
    while (y > 0) {
        if (y & 1)
            res = (res*x)%M ;
        y = y>>1;
        x = (x*x)%M;
    }
    return res%M;
}
const double PI = 3.141592653589793238463;
lli solve(){
    lli n;
    cin>>n;
    map<string, bool> mp1, mp2;
    mp1["a"] = true;
    // if(n == 1){
    //     cout<<"a\n";
    //     return 0;
    // }
    loop(i, 1, n){
        string res;
        // for(auto x : mp1)
        //     cout<<x.fi<<" ";
        // cout<<"\n";
        loop(j, 0, i+1){
            res.pb( 'a' + j );
            for(auto x : mp1){
                // lli len = res.length();
                // cout<<x.fi<<" ";
                if(x.fi.length() > j){
                    string temp = x.fi.substr(j);
                    // cout<<temp<<" ";
                    temp = res + temp;
                    mp2[temp] = true;
                }
                else{
                    mp2[res] = true;
                }
                // cout<<temp<<" ";
            }
        }
        mp1.clear();
        mp1 = mp2;
        mp2.clear();
    }
    for(auto x : mp1)
        cout<<x.fi<<"\n";
    return 0;
}
int main(){
    // fastio;
    lli t;
    // cin>>t;
    t = 1;
    while(t>0){
        t--;
        solve();
    }
    return 0;
}