#include <bits/stdc++.h>
 
using namespace std;
 
int n;
vector<vector<char>> a;
 
string s;
 
void rec(int i) {
	if(i == n) {
		cout << s << endl;
	} else {
		for(size_t j = 0; j < a[i].size(); j++) {
			if(!j || (j && a[i][j]!=a[i][j-1])) {
				s[i] = a[i][j];
				rec(i+1);
			}
		}
	}
}
 
int main() {
	a.push_back({'a','b','a'});
	a.push_back({'c','c'});
	a.push_back({'d','e','e','f'});
 
	n = a.size();
 
	for(int i = 0; i < n; i++) {
		sort(a[i].begin(), a[i].end());
		s += "#";
	}
 
	rec(0);
}

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