#include<bits/stdc++.h>
using namespace std;

int N;

void dfs(string s,char mx){
    if(s.length()==N){
        cout<<s<<endl;
    }
    else{
        for (char c ='a'; c<=mx;c++ ){
            dfs(s+c,((c==mx)? (char)(mx+1):mx));
        }
    }
}

int main(){
    cin>>N;
    dfs("",'a');
    return 0;
}