#include<bits/stdc++.h>
#define double long double
#define sqr(x) ((1ll*(x)*(x)))
#define dist(i,j) (sqrt(sqr(x[i]-x[j])+sqr(y[i]-y[j])))
#define A 65
using namespace std;
int x[1005],y[1005];
int n,k;
double jl[1005],dx[1005],dy[1005],md;
double ffabs(double x){
	if(x>0)return x;
	return -x;
}
double calc(double wz){
	int ll=1;
	double he=0;
	for(int i=1;i<=k;++i){
		double zz=wz+(i-1)*md;
		while(he+jl[ll+1]<zz)he+=jl[ll+1],++ll;
		double fl=(zz-he)/jl[ll+1];
		dx[i]=(1-fl)*x[ll]+fl*x[ll+1];
		dy[i]=(1-fl)*y[ll]+fl*y[ll+1];
	}
	dx[0]=dx[k],dy[0]=dy[k];
	dx[k+1]=dx[1],dy[k+1]=dy[1];
	dx[k+2]=dx[2],dy[k+2]=dy[2];
	double ans=0;
	for(int i=1;i<=k;++i){
		ans+=dx[i-1]*dy[i]-dy[i-1]*dx[i];
	}
	return ffabs(ans/2);
}
double solve(double L,double R){
	if(ffabs(R-L)<1e-10)return calc((L+R)/2);
	double zz=(R-L)/A,ans=1e18,wz=L;
	for(double xx=L;xx<=R;xx+=zz){
		double ss=calc(xx);
		if(ans>ss){
			ans=ss;
			wz=xx;
		}
	}
	return min(ans,solve(max(L,wz-4*zz),min(R,wz+4*zz)));
}
int main(){
	cin>>n>>k;
	for(int i=1;i<=n;++i)scanf("%d%d",&x[i],&y[i]);
	x[0]=x[n],y[0]=y[n];
	x[n+1]=x[1],y[n+1]=y[1];
	x[n+2]=x[2],y[n+2]=y[2];
	double zh=0;
	for(int i=1;i<=n+2;++i)jl[i]=dist(i,i-1);
	for(int i=1;i<=n;++i)zh+=jl[i];
	md=zh/k;
	printf("%.12Lf\n",solve(0,md));
	return 0;
}