#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
	int n;
	cin >> n ;
	vector<vector<int>> r(n+1,vector<int>(n+1,0));
	vector<int> dp(n+1,0);
	for(int i = 1; i < n; i++)
	{
		//cout << i << endl;
		for(int j = i+1; j <= n; j++)
		{
			cin >> r[i][j];
		}
	}
	

	
	for(int i = 2; i <= n; i++)
	{
		int min = 99999999;
		for(int j = 1; j < i; j++)
		{
			if(dp[j]+r[j][i]<min)
			{
				min = dp[j]+r[j][i];
			}
		}
		dp[i] = min;
	}
	cout << dp[n];
	return 0;
}