#include <iostream>

#include <cstdio>

#include <cstring>

#include <cstdlib>

#include <cmath>

#include <algorithm>

#include <string>

#include <vector>

#include <queue>

#include <map>

using namespace std;

#define N 100007

map<string,int> mp;

vector<int> G[];

int vis[],n,m,Maxdis,Maxtag;

struct node{

    int dis,u;

};

void dfs(int u)

{

    vis[u] = ;

    for(int i=;i<G[u].size();i++)

    {

        int v = G[u][i];

        if(!vis[v]) dfs(v);

    }

}

void bfs(int u)

{

    queue<node> que;

    memset(vis,,sizeof(vis));

    node now;

    now.dis = ;

    now.u = u;

    que.push(now);

    vis[u] = ;

    while(!que.empty())

    {

        int SZ = que.size();

        while(SZ--)

        {

            node tmp = que.front();

            que.pop();

            int dis = tmp.dis;

            int u = tmp.u;

            if(dis > Maxdis)

            {

                Maxdis = dis;

                Maxtag = u;

            }

            for(int i=;i<G[u].size();i++)

            {

                int v = G[u][i];

                if(!vis[v])

                {

                    now.u = v;

                    now.dis = dis+;

                    vis[v] = ;

                    que.push(now);

                }

            }

        }

    }

}

int main()

{

    int i,j;

    string S;

    while(scanf("%d",&n)!=EOF && n)

    {

        mp.clear();

        for(i=;i<=n;i++)

        {

            cin>>S;

            mp[S] = i;

            G[i].clear();

        }

        scanf("%d",&m);

        string A,B;

        for(i=;i<=m;i++)

        {

            cin>>A>>B;

            int a = mp[A], b = mp[B];

            G[a].push_back(b);

            G[b].push_back(a);

        }

        memset(vis,,sizeof(vis));

        dfs();

        int Link = ;

        for(i=;i<=n;i++)

            if(!vis[i]) Link = ;

        if(!Link)

        {

            puts("-1");

            continue;

        }

        Maxdis = , Maxtag = -;

        bfs();

        int S = Maxtag;

        Maxdis = , Maxtag = -;

        bfs(S);

        printf("%d\n",Maxdis);

    }

    return ;

}