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#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>

using namespace std;

#define FOR(i,n) for(int i=0;i<n;++i)
#define FORB(i,b,n) for(int i=b;i<n;++i)
#define REV(i,n) for(int i=n;i>=0;--i)
#define FOREACH(T, it, v) for(T::iterator it = v.begin(); it !=v.end(); ++it)
#define print(STRING,INT) printf("%s= %d\n", STRING, INT)
#define scan(INT) scanf("%d", &INT)


typedef unsigned int u32;
const int INF = (0u - 11)/2;

typedef long long ll;
typedef set<int> SI;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef set<long long> SL;
typedef map<int, int> MII;



int DEBUG_ = 1;



void log(char* S, long long a)
{
    if(DEBUG_)
    {
        printf("%s= %I64d\n", S, a);
    }
}

ll tab[2005][2005];


int main()
{	
	set<ll> S;
	int n, tmp;
	scan(n);
	FOR(i,n)
	{
		FORB(j,i,n)
		{
			scan(tmp);
			tab[i][i] = INF;
			tab[i][j+1]=tmp;
			tab[j+1][i]=tmp;
		//	A.insert(make_pair<int, int>(tmp, i * 2048 + j+1));
		}
	}

	n++;
	vector<int> V(n, 0);
	ll OFFSET = 2048;
	V[0] = 1;
	FOR(i,n)
	{
		if(!V[i])
		{
			S.insert(tab[0][i]*OFFSET + i);
		}
	}
	
	int a, b;
	ll out = 0;

	FORB(i,1,n)
	{
	//	cout << i << " " << n << endl;
		set<ll>::iterator it = S.begin();
		while(true)
		{
			a = (*it)/OFFSET;
			b = (*it)%OFFSET;
			S.erase(it++);

			if(!V[b])
			{
				out +=a;
				V[b] = 1;
				FOR(j,n)
				if(!V[j])
				{
					S.insert(tab[b][j]*OFFSET + j);
				}
				break;
			}
		}
	}
	cout << out << endl;
	return 0;
}