#include <cstdio>

 #include <cstring>

 #include <algorithm>

 #include <bitset>

 #include <queue>

 #include <unordered_map>

 using namespace std;

 const int maxn = 1e3+;

 int N,M;

 unordered_map<string,int> mp;

 bitset<maxn> G[maxn];

 bitset <maxn> to,unvis;

 queue <int> Q;

 int dis[maxn];

 int bfs(int rt)

 {

     while(!Q.empty()) Q.pop();

     Q.push(rt);

     dis[rt] = ;

     unvis.reset();

     for(int i=;i<=N;i++) unvis.set(i);

     int res = ;

     unvis.reset(rt);

     while(!Q.empty())

     {

         int u = Q.front();

         Q.pop();

         to = unvis & G[u];

         for(int v = to._Find_first(); v<=N; v = to._Find_next(v))

         {

             Q.push(v);

             unvis.reset(v);

             dis[v] = dis[u]+;

             res = max(res,dis[v]);

         }

     }

     //printf("")

     if(unvis.any()) return -;

     return res;

 }

 int main()

 {

     while(scanf("%d",&N) && N)

     {

         mp.clear();

         for(int i=;i<maxn;i++) G[i].reset();

         for(int i=;i<=N;i++)

         {

             char tmp[];

             scanf("%s",tmp);

             mp[tmp] = i;

         }

         scanf("%d",&M);

         for(int i=;i<M;i++)

         {

             char tmp1[],tmp2[];

             scanf("%s %s",tmp1,tmp2);

             int u = mp[tmp1],v = mp[tmp2];

             //printf("add edge:%d %d\n",u,v);

             G[u].set(v);G[v].set(u);

         }

         int ans = ;

         bool unconnected = ;

         for(int i=;i<=N;i++)

         {

             int res = bfs(i);

             if(res == -){unconnected = true;break;}

             ans = max(ans,res);

         }

         if(unconnected) printf("-1\n");

         else printf("%d\n",ans);

     }

 }