C++ :

#include<iostream>
#include<string>
#include<queue>
#include<cstdio>
#include<cstring>
using namespace std;
string s[22];char ld;
int n,maxx,tou[22],ans;
struct at{
	int cs[22];
};
int pd(string s1,string s2)
{
	int i=s1.size()-1,j=0;
	string x1="",x2="";
	x1+=s1[i];x2+=s2[j];
	while(i>0&&j<s2.size()-1)
	{
		if(x1==x2)
		    return 1;
		i--;j++;
		x1=s1[i]+x1;
		x2=x2+s2[j];
	}
	return 0;
}
string cj1(string s1,string s2)
{
    int i=s1.size()-1,j=0;
    string x1="",x2="";
	x1+=s1[i];x2+=s2[j];
	int i1,j1;
	while(i>0&&j<s2.size()-1)
	{
		if(x1==x2)
		{    
			i1=i;
			j1=j;
			break;
		}
		i--;j++;
		x1=s1[i]+x1;
		x2=x2+s2[j];
	}
	s2.erase(0,j1+1);
	string sx="";
	sx=s1+s2;
	//cout<<s1<<" + "<<s2<<" = "<<sx<<endl;
	return sx;
}
void bfs(int x)
{
	at c;
	for(int i=0;i<=20;i++)
	    c.cs[i]=0;
	queue <string> dr;
	queue <int> cd;
	queue <at> a;
	c.cs[x]++;
	a.push(c);
	if(s[x][0]!=ld)
	{
		string sx=""; sx+=ld;
		s[x].insert(0,sx);
	}
	dr.push(s[x]);
	cd.push(s[x].size());
	while(!dr.empty())
	{
		//cout<<dr.front()<<endl;
		for(int i=1;i<=n;i++)
		{
			//cout<<s[i]<<endl;
			if(a.front().cs[i]<2&&pd(dr.front(),s[i])==1)
			{
				for(int i=1;i<=n;i++)                        //回溯
            		c.cs[i]=a.front().cs[i];                //回溯
				//cout<<dr.front()<<" "<<s[i]<<endl;
				c.cs[i]=a.front().cs[i]+1;
				a.push(c);
				dr.push(cj1(dr.front(),s[i]));
				cd.push(cj1(dr.front(),s[i]).size());
				//cout<<"!"<<cj1(dr.front(),s[i])<<endl;
			}
		}
		if(cd.front()>maxx)
		{
			//cout<<dr.front()<<endl;
			maxx=cd.front();

		}
		a.pop();
		dr.pop();
		cd.pop();
	}
}
int main()
{
	//freopen("4.in","r",stdin);
	//freopen("4.ans","w",stdout);
	cin>>n;
	for(int i=1;i<=n;i++)
	    cin>>s[i];
	cin>>ld;
	for(int i=1;i<=n;i++)
	{
		//cout<<"   第"<<i<<"步"<<endl;
		bfs(i);
	}
	cout<<maxx;
	//while(1);
	return 0;
}