#include<iostream>
#include<cstdio>
#include<cmath>
#include<vector>
#include<cassert>
#define N 2000
#define inf 1e36
#define eps 1e-9
using namespace std;
int read()
{
    char c=0;
    int sum=0;
    while (c<'0'||c>'9') c=getchar();
    while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
    return sum;
}
void Adder(double &x,double d)
{
    x=(x<d)?x:d;
    return;
}
struct points
{
    double x,y;
};
points st[N+1];
double dist(points a,points b)
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
bool check_line(points a,points b,points c)
{
    return abs((b.y-a.y)*(c.x-a.x)-(c.y-a.y)*(b.x-a.x))<eps;
}
struct line
{
    double A,B,C;
};
points get_cross(line a,line b)
{
    points t=(points){(a.B*b.C-a.C*b.B)/(a.A*b.B-a.B*b.A),(a.A*b.C-a.C*b.A)/(a.B*b.A-a.A*b.B)};
    return t;
}
struct circle
{
    double x,y,r;
};
circle res;
circle make_little_circle(points a,points b)
{
    return (circle){(a.x+b.x)/2,(a.y+b.y)/2,dist(a,b)/2};
}
circle make_circle(points a,points b,points c)
{
    if (check_line(a,b,c))
    {
	if (a.x>b.x) swap(a.x,b.x);
	if (b.x>c.x) swap(b.x,c.x);
	if (a.x>b.x) swap(a.x,b.x);
	return make_little_circle(a,c);
    }
    else
    {
	points t=get_cross((line){2*(b.x-a.x),2*(b.y-a.y),a.x*a.x+a.y*a.y-b.x*b.x-b.y*b.y},(line){2*(c.x-a.x),2*(c.y-a.y),a.x*a.x+a.y*a.y-c.x*c.x-c.y*c.y});
	return (circle){t.x,t.y,dist(t,a)};
    }
}
bool check(circle a,points b)
{
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y)<=a.r*a.r+eps;
}
struct reads
{
    int num;
    double data;
};
int k,n,X[N+1],Y[N+1];
vector<reads>p[N+1];
double dp[N+1][N+1];
int main()
{
    n=read(),k=read(),X[1]=read();
    for (int i=1;i<=n;++i)
    {
	if (i!=1) X[i]=(Y[i-1]*233811181ll+1)%((1ll<<31)-1);
        Y[i]=(X[i]*233811181ll+1)%((1ll<<31)-1);
    }
    for (int i=1;i<=n;++i) st[i]=(points){(double)(X[i]),(double)(Y[i])};
    for (int i=n;i>=1;--i)
    {
	res=(circle){st[i].x,st[i].y,0},p[i].push_back((reads){i,0});
	for (int j=i-1;j>=1;--j)
	    if (!check(res,st[j]))
	    {
		res=(circle){st[j].x,st[j].y,0};
		for (int t=i;t>=j+1;--t)
		    if (!check(res,st[t]))
		    {
			res=make_little_circle(st[j],st[t]);
			for (int s=i;s>=t+1;--s)
			    if (!check(res,st[s]))
				res=make_circle(st[j],st[t],st[s]);
		    }
		p[i].push_back((reads){j,res.r});
	    }
    }
    for (int i=0;i<=k;++i)
	for (int j=1;j<=n;++j)
	    dp[i][j]=inf;
    dp[0][0]=0;
    for (int i=1;i<=k;++i)
	for (int j=1;j<=n;++j)
	{
	    Adder(dp[i][j],dp[i-1][j]);
	    for (int t=0;t+1<p[j].size();++t) Adder(dp[i][j],dp[i-1][p[j][t+1].num]+p[j][t].data);
	    Adder(dp[i][j],p[j].back().data);
	}
    printf("%0.6lf\n",dp[k][n]);
    return 0;
}