#include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <deque>
#include <complex>
#include <algorithm>
#include <cstdio>
#include <cmath>
#include <cstring>

#define REP(i,x) for(int i=0 ; i<(int)(x) ; i++)
#define ALL(x) (x).begin(),(x).end()
#define LL long long

using namespace std;

class AOJ1170{
	int D,N;
	string src;
	vector<string> piece;
	vector<vector<int> > go;
	vector<vector<int> > ac;
	vector<int> fail;
	string alp;
	vector<string> res;
	int L;
public:
	AOJ1170(){
		alp=".";
		for(char x='A' ; x<='Z' ; x++){
			alp.push_back(x);
		}
	}
	bool init(){
		scanf("%d%d",&D,&N);
		if(!(D||N))return false;
		char buf[128];
		scanf("%s",buf);
		src = string(buf);
		piece.resize(N);
		REP(i,N){
			scanf("%s",buf);
			piece[i] = string(buf);
		}
		sort(ALL(piece));
		piece.erase(unique(ALL(piece)),piece.end());
		L = piece[0].size()-1;
		res.clear();
		return true;
	}
	int get(int s,char x){
		return go[s][x]>=0?go[s][x]:(s==0?0:-1);
	}
	void makeAC(){
		int size = 0;
		map<int,map<char,int> > a;
		map<int,vector<int> > b;
		REP(i,piece.size()){
			int s = 0;
			REP(j,piece[i].size()){
				char x = piece[i][j];
				if(a.count(s)==0)a[s]=map<char,int>();
				if(a[s].count(x)==0)a[s][x]=++size;
				s = a[s][x];
			}
			if(b.count(s)==0)b[s] = vector<int>();
			b[s].push_back(i);
		}
		go.assign(size+1,vector<int>(256,-1));
		for(map<int,map<char,int> >::iterator it=a.begin() ; it!=a.end() ; it++){
			for(map<char,int>::iterator jt=it->second.begin() ; jt!=it->second.end() ; jt++){
				go[it->first][jt->first] = jt->second;
			}
		}
		ac.assign(size+1,vector<int>());
		for(map<int,vector<int> >::iterator it=b.begin() ; it!=b.end() ; it++){
			ac[it->first] = it->second;
		}
		
		fail.assign(size+1,0);
		queue<int> q;q.push(0);
		while(!q.empty()){
			int s = q.front();q.pop();
			REP(x,256)if(go[s][x]>=0){
				int next = go[s][x];
				q.push(next);
				if(s!=0){
					int f = fail[s];
					while(get(f,x)<0)f = fail[f];
					fail[next] = get(f,x);
					ac[next].insert(ac[next].end(),ALL(ac[fail[next]]));
				}
			}
		}
	}
	int getNext(int st,char x){
		int res = st;
		while(get(res,x)<0)res = fail[res];
		return get(res,x);
	}
	void dfs(int num,int d,int st,int cnt,string now){
		if(src.size()==num){
			if(ac[st].size())res.push_back(now);
			if(d>0){
				// insert
				REP(i,alp.size()){
					int next = getNext(st,alp[i]);
					int ncnt = ac[next].size()?L:cnt-1;
					if(next>0&&ncnt>=0){
						dfs(num,d-1,next,ncnt,now+alp[i]);
					}
				}
			}
		}
		else{
			//src
			int next = getNext(st,src[num]);
			int ncnt = ac[next].size()?L:cnt-1;
			if(next>0&&ncnt>=0)dfs(num+1,d,next,ncnt,now+src[num]);
			if(d>0){
				// insert
				// change
				REP(i,alp.size()){
					next = getNext(st,alp[i]);
					ncnt = ac[next].size()?L:cnt-1;
					if(next>0&&ncnt>=0){
						dfs(num,d-1,next,ncnt,now+alp[i]);
						dfs(num+1,d-1,next,ncnt,now+alp[i]);
					}
				}
				// delete
				dfs(num+1,d-1,st,cnt,now);
			}
		}
	}
	void solve(){
		dfs(0,D,0,L,"");
		sort(ALL(res));
		res.erase(unique(ALL(res)),res.end());
		printf("%d\n",res.size());
		if(res.size()<=5){
			REP(i,res.size())printf("%s\n",res[i].c_str());
		}
	}
};

int main(){
	AOJ1170 solver;
	while(solver.init()){
		solver.makeAC();
		solver.solve();
	}
	return 0;
}