#include<bits/stdc++.h>
using namespace std;

#define db long double
#define eps 1e-9
const int _ = 1003;
struct vec{
	db x , y; vec(db _x = 0 , db _y = 0) : x(_x) , y(_y){}
	friend vec operator +(vec p , vec q){return vec(p.x + q.x , p.y + q.y);}
	friend vec operator -(vec p , vec q){return vec(p.x - q.x , p.y - q.y);}
	friend vec operator *(vec p , db q){return vec(p.x * q , p.y * q);}
	friend db operator *(vec p , vec q){return p.x * q.x + p.y * q.y;}
	friend db operator %(vec p , vec q){return p.x * q.y - p.y * q.x;}
	db len(){return sqrt(x * x + y * y);}
}node[_]; int N , K; db len[_];

int main(){
	cin >> N >> K; for(int i = 1 ; i <= N ; ++i) cin >> node[i].x >> node[i].y;
	node[0] = node[N]; db allen = 0; for(int i = 0 ; i < N ; ++i) allen += (node[i] - node[i + 1]).len();
	for(int i = 0 ; i < N ; ++i) len[i] = (node[i + 1] - node[i]).len();
	vector < vec > pos; vector < db > lim; vector < int > p;
	for(int i = 0 ; i < K ; ++i){
		db tar = allen / K * i;
		for(int j = 0 ; j < N ; ++j)
			if(len[j] < tar) tar -= len[j];
			else{pos.push_back(node[j] + (node[j + 1] - node[j]) * (tar / len[j])); p.push_back(j); lim.push_back(len[j] - tar); break;}
	}
	auto check = [&](db val){
		vector < vec > npos;
		for(int i = 0 ; i < K ; ++i) npos.push_back(pos[i] + (node[p[i] + 1] - node[p[i]]) * (val / len[p[i]]));
		double ans = 0; for(int i = 1 ; i + 1 < npos.size() ; ++i) ans += (npos[i] - npos[0]) % (npos[i + 1] - npos[0]);
		return abs(ans) / 2;
	};
	double ans = 1e18;
	while(p.back() != N){
		db minlim = 1e9; for(auto t : lim) minlim = min(minlim , t);
		db L = 0 , R = minlim;
		//for(int j = 0 ; j < 500 ; ++j) ans = min(ans , check(minlim / 500 * j));
		for(int i = 1 ; i <= 40 ; ++i){
			check(L + (R - L) / 3) > check(R - (R - L) / 3) ? L = L + (R - L) / 3 : R = R - (R - L) / 3;
		}
		ans = min(ans , min(check(0) , min(check(minlim) , check(L))));
		for(int i = 0 ; i < K ; ++i){
			lim[i] -= minlim; pos[i] = pos[i] + (node[p[i] + 1] - node[p[i]]) * (minlim / len[p[i]]);
			if(lim[i] < eps){++p[i]; lim[i] = len[p[i]];}
		}
	}
	cout << fixed << setprecision(15) << ans; return 0;
}