#include "bits/stdc++.h"
#include<unordered_map>
#include<unordered_set>
#pragma warning(disable:4996)
using namespace std;
using ld = long double;
template<class T>
using Table = vector<vector<T>>;
const ld eps=1e-9;

//// < "D:\D_Download\Visual Studio 2015\Projects\programing_contest_c++\Debug\a.txt" > "D:\D_Download\Visual Studio 2015\Projects\programing_contest_c++\Debug\b.answer"

typedef double Weight;

struct Edge {
	int src, dst;
	Weight weight;
	int id;
	Edge(int src_, int dst_, Weight weight_,const int id_) :
		src(src_), dst(dst_), weight(weight_),id(id_) { }
	Edge(int src, int dst, Weight weight) :
		src(src), dst(dst), weight(weight) { }
	Edge() :src(0), dst(0), weight(0) {

	}
};
const Weight INF = 1e18;
const Weight ZERO = 0;
bool operator < (const Edge &e, const Edge &f) {
	return e.weight != f.weight ? e.weight > f.weight : // !!INVERSE!!
	e.src != f.src ? e.src < f.src : e.dst < f.dst;
}
typedef vector<Edge> Edges;
typedef vector<Edges> Graph;
ld getdis(const vector<ld>&f, const vector<ld>&t) {
	ld amin = -100;
	ld amax = 100;
	int n = 50;
	while (n--) {
		ld amid0 = (amin*2 + amax) /3;
		ld amid1 = (amin + amax * 2) / 3;
		ld len0 = 0;
		ld len1 = 0;
		{
		
			for (int i = 0; i < f.size(); ++i) {
				len0 += (t[i] - amid0*f[i])*(t[i] - amid0*f[i]);
			}
			for (int i = 0; i < f.size(); ++i) {
				len1 += (t[i] - amid1*f[i])*(t[i] - amid1*f[i]);
			}
		}
		if (len0<len1) {
			amax = amid1;
		}
		else {
			amin = amid0;
		}
		if (!n)return len0;
	}
}

namespace getcycle {
	vector<Edge>get_cycle(const Graph&g,const int start) {
		vector<Edge>prev_es(g.size());
		for (auto es : g) {
			for (auto e : es) {
				prev_es[e.dst] = e;
			}
		}
		for (int i = 0; i < g.size(); ++i) {
			if (i == start)continue;
			int now = i;
			vector<Edge>cycles;
			vector<int>comes(g.size(),-1);
			comes[now] = 0;
			int num = 1;
			while (1) {
				cycles.emplace_back(prev_es[now]);
				now = prev_es[now].src;
				if (comes[now]!=-1) {
					cycles = vector < Edge>(cycles.begin() + comes[now], cycles.end());
					reverse(cycles.begin(), cycles.end());
					return cycles;
				}
				else if (now == start) {
					break;
				}
				comes[now] = num++;
			}
		}
		return vector<Edge>(0);
	}
}

//aoj2309???varify??????????????£??????????????§????????????????????????
pair<Weight,Graph> chu_liu(const Graph&g, const int start,const int e_size) {

	vector<Edge>cycle_edges;
	ld total_len = 0;
	{
		Graph tree(g.size());
		{
			Graph revg(g.size());


			for (auto es : g) {
				for (auto e : es) {
					revg[e.dst].emplace_back(e.dst, e.src, e.weight);
				}
			}
			for (int node = 0; node < g.size(); ++node) {
				if (node == start)continue;
				else {
					Weight amin = INF;
					Edge min_edge;
					for (auto reve : revg[node]) {
						if (amin > reve.weight) {
							amin = reve.weight;
							min_edge = Edge(reve.dst, reve.src, reve.weight);
						}
					}
					if (amin < INF) {
						total_len += min_edge.weight;
						tree[min_edge.src].emplace_back(min_edge);
					}
				}
			}
		}
		cycle_edges = getcycle::get_cycle(tree, start);
	}
	
	if (cycle_edges.empty()) {
		return make_pair(total_len,g);
	}
	else {
		vector<bool>node_is_cycle(g.size());

		/*????´???°???Edge?????°????????§??????*/
		vector<int>edge_is_cycle(e_size);

		vector<Weight>prev_lens(g.size(), ZERO);
		
		for (auto ce : cycle_edges) {
			node_is_cycle[ce.src] = true;
			prev_lens[ce.dst] = ce.weight;
		}
		Graph newg(g.size());
		const int compress = cycle_edges[0].src;
		/*????´???°???Edge?????°????????§??????*/
		vector<Edge>memo(e_size);
		for (int s = 0; s < g.size();++s){
			bool src_is_cycle = node_is_cycle[s];
			for (auto e : g[s]) {
				memo[e.id] = e;
				bool dst_is_cycle = node_is_cycle[e.dst];
				if (src_is_cycle&&dst_is_cycle) {
					continue;
				}
				else if (src_is_cycle) {
					e.src = compress;
				}
				else if (dst_is_cycle) {
					e.weight -= prev_lens[e.dst];
					e.dst = compress;
				}
				newg[e.src].push_back(e);
			}
		}
		auto p=chu_liu(newg, start, e_size);
		Graph compress_tree(p.second);
		Graph ans_tree(g.size());
		for (auto es : compress_tree) {
			for (auto e : es) {
				const Edge prev_edge(memo[e.id]);
				ans_tree[prev_edge.src].emplace_back(prev_edge);
			}
		}
		Weight cycle_len = 0;
		for (auto e : cycle_edges) {
			cycle_len += e.weight;
		}
		return make_pair(p.first + cycle_len, ans_tree);
	}
}

int main() {
	int N, M; cin >> N >> M;
	vector<vector<ld>>vecs(M,vector<ld>(N));
	vector<vector<ld>>edges(M, vector<ld > (M));
	for (int i = 0; i < M; ++i) {
		for (int j = 0; j < N; ++j) {
			cin >> vecs[i][j];
		}
	}
	const int start = 0;
	const int node = 1;
	Graph g(M+1);
	int id = 0;
	for (int i = 0; i < M; ++i) {
		ld inidis = 0;
		for (int j = 0; j < N; ++j) {
			inidis += vecs[i][j] * vecs[i][j];
		}
		g[start].emplace_back(start, node + i, inidis,id++);
		for (int j = 0; j < M; ++j) {
			if (i != j) {
				ld dis = getdis(vecs[i], vecs[j]);
				g[node + i].emplace_back(node + i, node + j, dis, id++);
			}
		}
	}
	auto p=chu_liu(g, start,(g.size())*((g.size()+1)));
	cout <<fixed<<setprecision(22)<< p.first << endl;
	return 0;
}

Measured memory_bytes: 45772