#include<bits/stdc++.h>
using namespace std;
int n,a,f[201];
int main(){
	cin >> n;
	for(int i = 1;i <= n;i++)
		for(int j = i + 1;j <= n;j++)
		{
			scanf("%d",&a);
			if(f[j] = 0 || f[j] > f[i] + a)
                f[j] = f[i] + a;
		}
	cout << f[n] << endl;
	return 0;
}