求hack

/*
    Luogu name: Symbolize
    Luogu uid: 672793
*/
#include<bits/stdc++.h>
#define int long long
#define pii pair<int,int>
#define x first
#define y second
#define rep1(i,l,r) for(int i=l;i<=r;++i)
#define rep2(i,l,r) for(int i=l;i>=r;--i)
#define rep3(i,x,y,z) for(int i=x[y];~i;i=z[i])
#define rep4(i,x) for(auto i:x)
#define debug() puts("----------")
const int N=1e5+10;
const int inf=0x3f3f3f3f3f3f3f3f;
using namespace std;
int n,k;
string s[N],t[N];
int read()
{
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-') f=-1;
        ch=getchar();
    }
    while(ch>='0'&&ch<='9')
    {
        x=(x<<1)+(x<<3)+(ch^48);
        ch=getchar();
    }
    return f*x;
}
bool cmp(string s1,string s2)
{
	int l1=s1.length(),l2=s2.length();
//	cout<<s1<<' '<<s2<<"\n";
	rep1(i,0,min(l1,l2)-1)
	{
//		cout<<s1[i]<<' '<<s2[i]<<"\n";
		if(s1[i]>s2[i]) return 1;
		if(s1[i]<s2[i]) return 0;
	}
	if(l1>l2) return 1;
	return 0;
}
signed main()
{
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
    n=read();
    k=read();
    rep1(i,1,n) cin>>s[i];
    string now=s[1];
    rep1(i,2,n)
    {
        int l1=now.size(),l2=s[i].size();
        int len=l1*l2/__gcd(l1,l2);
        string s1="",s2="";
        rep1(j,1,len/l1) s1+=now;
        rep1(j,1,len/l2) s2+=s[i];
        if(s1>s2||(s1==s2&&l1>l2)) now=s[i];
    }
    rep1(i,1,k-10) cout<<now;
    k=min(k,10ll);
    rep2(i,k,1)
    {
        int id=-1;
        rep1(j,1,n) 
        {
            t[j]="";
            rep1(p,1,i) t[j]+=s[j];
            if(id==-1||!cmp(t[j],t[id])) id=j;
        }
        cout<<s[id];
    }
    putchar('\n');
    return 0;
}
/*
cbcbcbabcbcbc

3 4
cbcbcbab
cb
c
*/