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#include<algorithm>
#include<iostream>
#include<vector>

struct Query
{
	unsigned c, a, b;

	Query(unsigned c, unsigned a, unsigned b): c(c), a(a), b(b) {}

	bool operator<(const Query &q) const
	{
		return c < q.c;
	}
};

unsigned parent[2001], rank[2001];

unsigned getparent(unsigned a)
{
	if(a != parent[a])
		parent[a] = getparent(parent[a]);

	return parent[a];
}

int main()
{
	std::ios_base::sync_with_stdio(false);

	unsigned n;
	std::cin >> n;
	std::vector<Query> v;
	v.reserve(n * (n + 1) / 2);
	for(unsigned i = 0; i < n; ++i)
		for(unsigned j = i + 1; j <= n; ++j)
		{
			unsigned c;
			std::cin >> c;
			v.emplace_back(c, i, j);
		}

	std::sort(v.begin(), v.end());

	for(unsigned i = 0; i <= n; ++i)
	{
		parent[i] = i;
		rank[i] = 0;
	}

	unsigned long long w = 0;
	unsigned count = 0;
	for(const Query &q: v)
	{
		unsigned a = getparent(q.a), b = getparent(q.b);

		if(a != b)
		{
			if(rank[a] < rank[b])
				std::swap(a, b);
			if(rank[a] == rank[b])
				++rank[a];
			parent[b] = a;

			w += q.c;

			if(++count == n)
				break;
		}
	}

	std::cout << w << std::endl;

	return 0;
}