#include<bits/stdc++.h>
using namespace std;
double R,eps=1e-10;
struct P{double x,y;}a[2005],O;
double dis(P x,P y){return sqrt((x.x-y.x)*(x.x-y.x)+(x.y-y.y)*(x.y-y.y));}
P center(P x,P y,P z)
{
    double a1=y.x-x.x,b1=y.y-x.y,
            c1=(a1*a1+b1*b1)/2,a2=z.x-x.x,
            b2=z.y-x.y,c2=(a2*a2+b2*b2)/2,
            d=a1*b2-a2*b1;
    return (P){x.x+(c1*b2-c2*b1)/d,x.y+(a1*c2-a2*c1)/d};
}
double cal(int n,P *b){
    int i,j,k;
    for(i=0;i<n;i++)a[i]=b[i];
    for(i=0;i<n;i++)swap(a[rand()%n],a[i]);
    for(O=a[0],R=0,i=1;i<n;i++)if(dis(a[i],O)>R+eps)
            for(O=a[i],R=0,j=0;j<i;++j)if(dis(a[j],O)>R+eps){
                    O=(P){(a[i].x+a[j].x)/2,(a[i].y+a[j].y)/2},R=dis(O,a[i]);
                    for(k=0;k<j;k++)if(dis(a[k],O)>R+eps)O=center(a[k],a[j],a[i]),R=dis(O,a[i]);
                }
    return R;
}
P dot[2005];
double dp[2005][2005],pp[2005][2005];
int n,k;

long long x[2005],y[2005];
long long nxt(long long x){
    return (x*233811181ll+1)%((1ll<<31)-1);
}

int main(){
    srand(time(0));
    scanf("%d%d%lld",&n,&k,&x[1]);
    if (k>=n){
        printf("0.0\n");
        return 0;
    }
    y[1]=nxt(x[1]);
    for (int i=2;i<=n;i++) {
        x[i] = nxt(y[i - 1]);
        y[i] = nxt(x[i]);
    }
    for (int i=0;i<n;i++) dot[i]={x[i+1],y[i+1]};

    double final_res = 1e30;
    if (1ll*n*n*k>=10000000) {
        for (int i = 0; i + n - k + 1 - 1 < n; i++) {
            double r = cal(n - k + 1, dot + i);
            final_res = min(r, final_res);
        }
    } else{
        for (int i=0;i<=n;i++)
            for (int j=0;j<=k;j++) dp[i][j]=1e30;
        dp[0][0]=0;
        for (int i=0;i<n;i++)
            for (int j=i+1;j<=n;j++) pp[i][j]=cal(j-i,dot+i);
        for (int i=0;i<=n;i++)
            for (int j=0;j<=min(i,k);j++)
                for (int l=i+1;l<=n;l++) dp[l][j+1]=min(dp[l][j+1],dp[i][j]+pp[i][l]);
        final_res=dp[n][k];
    }
//     1319350480.8007326126
    printf("%.10f\n",final_res);
}