1 #include<map>
  2 #include<queue>
  3 #include<cstdio>
  4 #include<string>
  5 #include<cstring>
  6 #include<algorithm>
  7 using namespace std;
  8 
  9 struct edge
 10 {
 11     int from,to,time;
 12     edge(int u,int v,int w):from(u),to(v),time(w){};
 13 };
 14 
 15 struct Node
 16 {
 17     int st;
 18     int ed;
 19     int val;
 20 }node[1005];
 21 
 22 struct heapnode
 23 {
 24     int u,d;
 25     bool operator < (const heapnode &temp)const
 26     {
 27         return d>temp.d;
 28     }
 29 };
 30 
 31 const int inf =0x3f3f3f3f;
 32 map<string,int>key;
 33 vector<edge>edges;
 34 vector<int>G[1005];
 35 int d[1005],vis[1005];
 36 int num,n;
 37 
 38 void init()
 39 {
 40     for(int i=0;i<n;i++)
 41     G[i].clear();
 42     edges.clear();
 43     memset(vis,0,sizeof(vis));
 44     key.clear();
 45 }
 46 
 47 void addedge(int u,int v,int w)
 48 {
 49     edges.push_back(edge(u,v,w));
 50     int m=edges.size();
 51     G[u].push_back(m-1);
 52 }
 53 
 54 void dijkstra(int S)
 55 {
 56     priority_queue<heapnode>q;
 57     q.push((heapnode){S,0});
 58     for(int i=0;i<n;i++)
 59     d[i]=inf;
 60     d[S]=0;
 61     while(!q.empty())
 62     {
 63         int u=q.top().u;
 64         q.pop();
 65         if(vis[u])
 66         continue;
 67         vis[u]=1;
 68         for(int i=0;i<G[u].size();i++)
 69         {
 70             edge& e=edges[G[u][i]];
 71             if(d[e.to]>d[u]+e.time)
 72             {
 73                 d[e.to]=d[u]+e.time;
 74                 q.push((heapnode){e.to,d[e.to]});
 75             }
 76         }
 77     }
 78 }
 79 
 80 int main()
 81 {
 82     //freopen("in.txt","r",stdin);
 83     char s[105],sub1[5],sub2[5];
 84     string temp1,temp2;
 85     int i,j,val,t,k;
 86     while(scanf("%d",&t),t)
 87     {
 88         j=num=0;
 89         n=t;
 90         init();
 91         while(t--)
 92         {
 93             scanf("%d %s",&val,s);
 94             int len=strlen(s);
 95             for(i=0;i<4;i++)
 96             sub1[i]=s[i];
 97             sub1[i]=‘\0‘;
 98             temp1=sub1;
 99             if(!key.count(temp1))
100             key[temp1]=num++;
101             for(k=0,i=len-4;i<=len;i++,k++)
102             sub2[k]=s[i];
103             temp2=sub2;
104             if(!key.count(temp2))
105             key[temp2]=num++;
106             node[j].st=key[temp1];
107             node[j].ed=key[temp2];
108             node[j].val=val;
109             for(int k=0;k<j;k++)
110             if(node[k].ed==node[j].st)
111             addedge(k,j,node[k].val);
112             else if(node[j].ed==node[k].st)
113             addedge(j,k,node[j].val);
114             else;
115             j++;
116         }
117         dijkstra(0);
118         if(d[n-1]==inf)
119         printf("-1\n");
120         else
121         printf("%d\n",d[n-1]);
122     }
123     return 0;
124 }