#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N = 210;
const LL INF = 0x3f3f3f3f3f3f3f3fll;
struct edge
{
	LL x,cap,cost,rev;
};
vector<edge> e[N];
int n,m,s,t;
bool st[N];
LL d[N];
int it[N];
void add(int a,int b,LL c,LL d)
{
	e[a].push_back({b,c,d,(LL)e[b].size()});
	e[b].push_back({a,0,-d,(LL)e[a].size() - 1});
}
void spfa()
{
	memset(d,0x3f,sizeof d);
	queue<int> q;
	d[s] = 0;
	q.push(s);
	st[s] = 1;
	while(!q.empty())
	{
		int u = q.front();
		q.pop();
		st[u] = 0;
		for(auto t : e[u])
			if(t.cap > 0 && d[t.x] > d[u] + t.cost)
			{
				d[t.x] = d[u] + t.cost;
				if(!st[t.x]) q.push(t.x),st[t.x] = 1;
			}
	}
}
LL res;
LL dfs(int u,LL f)
{
	if(u == t) return f;
	st[u] = 1;
	for(int &i = it[u]; i < e[u].size(); i ++)
	{
		edge &t = e[u][i]; 
		if(!st[t.x] && d[u] + t.cost == d[t.x] && t.cap > 0)
		{
			LL d = dfs(t.x,min(f,t.cap));
			if(d > 0)
			{
				t.cap -= d;
				e[t.x][t.rev].cap += d;
				res += d * t.cost;
				st[u] = 0;
				return d;
			}
		}
	}
	st[u] = 0; 
	return 0;
}
LL dinic() 
{
	LL flow = 0;
	while(1)
	{
		spfa();
		if(d[t] == INF) break;
		memset(it,0,sizeof it);
		LL d = dfs(s,1e18);
		while(d > 0)
		{
			flow += d;
			d = dfs(s,1e18);
		}
	}
	return flow;
}
string str[N];
unordered_map<string,int> mp;
void dfs1(int u)
{
	cout<<str[u]<<endl;
	st[u] = 1;
	for(auto &x : e[u])
	{
		if(x.x > n && x.x <= 2 * n && x.cap == 0)
		{
			dfs1(x.x - n);
			return;
		}
	}
}
void dfs2(int u)
{
	st[u] = 1;
	for(auto &x : e[u])
	{
		if(x.x > n && x.x <= 2 * n && x.cap == 0 && !st[x.x - n])
		{
			dfs2(x.x - n);
		}
	}
	cout<<str[u]<<endl;
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cin>>n>>m;
	s = 0,t = 2 * n + 1;
	bool flag = 0;
	for(int i = 1; i <= n; i ++)
	{
		cin>>str[i];
		mp[str[i]] = i;
		if(i != 1 && i != n) add(i + n,i,1,-1);
		else add(i + n,i,2,-1);
	}
	for(int i = 1; i <= m; i ++)
	{
		string x,y;
		cin>>x>>y;
		int a = mp[x],b = mp[y];
		if(a > b) swap(a,b);
		flag |= (a == 1 && b == n);
		add(a,b + n,1,0);
	}
	add(s,n + 1,1e9,0);
	add(n,t,1e9,0);
	LL f = dinic();
	if(f == 1 && flag)
	{
		cout<<2<<endl<<str[1]<<endl<<str[n]<<endl<<str[1]<<endl;
		return 0;
	}
	if(f != 2)
	{
		cout<<"No Solution!\n";
		return 0;
	}
	cout<<- res - 2<<endl;
	dfs1(1);
	dfs2(1);
	return 0;
}