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

const int N = 30;
int n;
stack<int> st;
int res[N][N];
int path[N];
int cnt = 0;
int hh = 0;

void dfs(int u)
{
    if(u == n+1)
    {
        stack<int> tmp = st;
        int pre = hh;
        while(tmp.size())
        {
            path[hh++] = tmp.top();
            tmp.pop();
        }
        for(int i = 0; i<hh; i++)
            res[cnt][i] = path[i];
        hh = pre;
        cnt++;
        return;
    }
    if(st.size())
    {
        int x = st.top();
        path[hh++] = x;
        st.pop();
        dfs(u);
        hh--;
        st.push(x);
    }
    st.push(u);
    dfs(u+1);
    st.pop();
}
int main()
{
    cin>>n;
    dfs(1);
    for(int i = 0; i<cnt; i++)
    {
        for(int j = 0; j<n; j++)
        {
            cout<<char('a'+res[i][j]-1);
        }
        cout<<endl;
    }
}