#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------


bitset<101> B;
int N,K;
string A[101];
set<string> C;
string pre;

void dfs(int id,string cur) {
	if(C.size()>3*N) return;
	if(id==N) {
		C.insert(cur);
		return;
	}
	
	int i;
	FOR(i,N) if(B[i]==0) {
		if(i&&A[i]==A[i-1]&&B[i-1]==0) continue;
		B[i]=1;
		dfs(id+1,cur+A[i]);
		B[i]=0;
	}
}


void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>K;
	FOR(i,N) cin>>A[i];
	FOR(i,N) {
		FOR(j,N-1) {
			if(A[j]+A[j+1]<A[j+1]+A[j]||(A[j]+A[j+1]==A[j+1]+A[j]&&A[j]<A[j+1])) {
				swap(A[j],A[j+1]);
			}
		}
	}
	
	dfs(0,"");
	
	vector<string> V;
	FORR(s,C) V.push_back(s);
	sort(ALL(V));
	reverse(ALL(V));
	V.resize(K);
	FORR(v,V) cout<<v<<endl;
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}