#include<bits/stdc++.h>
using namespace std;
char x[5];
void combination(int pos,char letter)
{
    if(pos>3)
    {
        for(int i=1;i<=3;i++)
            cout<<x[i]<<" ";
        cout<<endl;
        return;
    }
     x[pos]=letter;
    cout<<x[pos]<<endl;
    if(pos==1)
    {
        combination(pos+1,'a');
        combination(pos+1,'b');
        combination(pos+1,'c');
    }
    else
    {
        if(letter=='a')
        {
            combination(pos+1,'b');
            combination(pos+1,'c');
        }
        else if(letter=='b')
        {
            combination(pos+1,'a');
            combination(pos+1,'c');
        }
        else
        {
            combination(pos+1,'a');
            combination(pos+1,'b');
        }

    }
}
int main()
{
    combination(1,'a');
    return 0;
}