#include <iostream>
#include <cstring>
#include <queue>
#include <cmath>
using namespace std;
const int N = 500;
typedef pair<int,int> PII;

int n, dist[N], h[N], ne[N], e[N], w[N], idx, st[N];

void add(int a, int b, int c) {
	w[idx] = c, e[idx] = b, ne[idx] = h[a], h[a] = idx++;
}
//堆优化版dijkstra
int main()
{
	cin >> n;
	memset(h, -1, sizeof(h));
	memset(dist, 0x3f, sizeof dist);
	for(int i = 1; i <= n; i++) {
		for(int j = i + 1; j <= n; j++) {
			int c; cin >> c;
			add(i, j, c);
		}
	}
	priority_queue< PII, vector<PII>, greater<PII> > heap;
	dist[1] = 0;
	heap.push({0, 1});
	while(heap.size()) {
		auto t = heap.top(); heap.pop();
		int ver = t.second, distance = t.first;
		if(st[ver]) continue;
		st[ver] = 1;
		for(int i = h[ver]; i != -1; i = ne[i]) {
			int v = e[i];
			if(!st[v] && dist[v] > dist[ver] + w[i]) dist[v] = dist[ver] + w[i];
			heap.push({dist[v], v});
		}

	} 
	cout << dist[n];
	return 0;
}