#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <math.h>
#include <queue>
using namespace std;
const int N = 1005;
const int INF = 99999999;
struct Node{
    char s[5],e[5];
    int w;
}node[N];
int graph[N][N];
int n;
void deal(char s[],int id){
    for(int i=0;i<4;i++) node[id].s[i] = s[i];
    int len = strlen(s);
    int k =0;
    for(int i=len-4;i<len;i++) {
        node[id].e[k++] = s[i];
    }
}
int low[N];
bool vis[N];
void dijkstra(int s){
    memset(vis,false,sizeof(vis));
    for(int i=0;i<n;i++){
        low[i] = (i==s)?0:graph[s][i];
    }
    vis[s] = true;
    for(int i=1;i<n;i++){
        int Min = INF;
        for(int j=0;j<n;j++){
            if(Min>low[j]&&!vis[j]){
                s=j;
                Min = low[j];
            }
        }
        vis[s] = true;
        for(int j=0;j<n;j++){
            if(low[j]>low[s]+graph[s][j]&&!vis[j]){
                low[j]=low[s]+graph[s][j];
            }
        }
    }
}
int main()
{
    while(scanf("%d",&n)!=EOF&&n){
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                if(i==j) graph[i][j] = 0;
                else graph[i][j]=INF;
            }
        }
        for(int i=0;i<n;i++){
            char str[N];
            scanf("%d%s",&node[i].w,str);
            deal(str,i);
        }
        for(int i=0;i<n;i++){
            for(int j=0;j<n;j++){
                if(strcmp(node[i].e,node[j].s)==0) graph[i][j] = node[i].w;
            }
        }
        dijkstra(0);
        if(low[n-1]>=INF) printf("-1\n");
        else printf("%d\n",low[n-1]);
    }
    return 0;
}