uva_423

/*
 Author                             :     unlucky_13
 Probs_link                         :
 Category                           : TOO easy to_int() function is nice
 Algorithm_Used                     : FW
 */

#include<cstdio>
#include<sstream>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<algorithm>
#include<set>
#include<queue>
#include<stack>
#include<list>
#include<iostream>
#include<fstream>
#include<numeric>
#include<string>
#include<vector>
#include<cstring>
#include<map>
#include<iterator>
#define LL long long int
const long long int inf = 2147483647;
//const int min=;
//const int maxn=;
using namespace std;
int to_int(char *s){

    int ret=0 ;
    for(int i=0;s[i]!='\0';i++){
        ret = ret*10+(s[i]-'0') ;
    }
    //cout<<ret<<endl ;
    return ret ;

}

int main() {

     freopen("C:\\Users\\Mazhar\\Desktop\\in.txt", "r", stdin);
     int n ,dis[200][200];
     char in[100] ;
     while(scanf("%d",&n)!=EOF){
         /*for(int i=0;i<=n;i++){
             for(int j=0;j<=n;j++) dis[i][j]=inf ;
         }*/
         for(int i=2;i<=n;i++){
             for(int j=1;j<i;j++){
                 scanf("%s",in) ;
                 if(in[0]=='x') dis[i][j] = dis[j][i] = inf ;
                 else dis[i][j] = dis[j][i]= to_int(in)  ;
             }
         }

         //FW
         for(int k=1;k<=n;k++){
             for(int i=1;i<=n;i++){
                 for(int j=1;j<=n;j++){
                     if(dis[i][k]<inf && dis[k][j]<inf && dis[i][j]>dis[i][k]+dis[k][j]){
                         dis[i][j] = dis[i][k]+dis[k][j] ;
                         //cout<<"updated"<<endl ;
                     }
                 }
             }
         }
         int ans = 0 ;
         for(int i=2;i<=n;i++){
            // cout<<dis[1][i]<<endl ;
             ans = max(ans,dis[1][i]) ;
         }

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


     }


    return 0;
}