#include<bits/stdc++.h>
//#include <iostream>
//#include <cstring>
//#pragma GCC optimize(2)
#include<time.h>
using namespace std;
#define maxn 205
#define inf 1e18
#define eps 0.00001
typedef long long ll;
const ll mod = 1e9+7;
const double pi = acos(-1);

ll n,vis[maxn][maxn],dis[maxn];
bool flag[maxn];

void dij()
{

   ll now = 1;

   for(ll i = 2; i <= n; i++)
   {
       dis[i] = inf;
   }

   flag[1] = 1;


   for(ll i = 1; i <= n; i++)
   {
       ll temp = inf;

       for(ll j = 1 ; j <= n; j++)
       {
           if(flag[j] == 0 && dis[j] < temp)
           {
               temp = dis[j];
               now = j;
           }
       }

       flag[now] = 1;

       for(ll j = 1; j <= n; j++)
            dis[j] = min(dis[j],dis[now]+vis[now][j]);

   }
   return ;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);

    //freopen("D:\\test1.in","w",stdout);
    //srand((int)time(0));

    cin >> n;

    for(ll i = 1; i <= n; i++)
        for(ll j = 1; j <= n; j++)
            vis[i][j] = inf;

    for(ll i = 1; i <= n-1; i++)
    {
        for(ll j = 1; j <= n - i; j++)
        {
            ll temp;
            cin >> temp;
            vis[i][i+j] = temp;

            if(i == j)
                vis[i][j] = 0;
        }
    }

    dij();

    cout << dis[n] << endl;

    return 0;
}