#include<cstdio>

#include<cmath>

#include<iostream>

using namespace std;

typedef long long ll;

typedef double real;

#define setfire(name) freopen(#name".in","r",stdin);freopen(#name".out","w",stdout);

#define fre(name) freopen(#name".txt","r",stdin);

#define debug(x) cout<<#x<<" "<<x<<'\n';

#ifdef WIN32

#define LL "%I64d"

#else

#define LL "%lld"

#endif

const int N=;

const real inf=1e14;

struct M{int x,y;}a[N];

int n,row,line,S,T,q[N*];bool vis[N*];

real ans,g[N][N],dis[N];

double get_dis(M a,M b){

    int tx=a.x-b.x,ty=a.y-b.y;

    return sqrt(tx*tx+ty*ty);

}

void init(){

    scanf("%d%d%d",&n,&row,&line);S=n+;T=S+;

    for(int i=,x,y;i<=n;i++) scanf("%d%d",&a[i].x,&a[i].y);

}

void mapping(){

    for(int i=;i<=n;i++)

//        g[S][i]=g[i][S]=min(a[i].x-1,row-a[i].x),//居然还90

//        g[T][i]=g[i][T]=min(a[i].y-1,line-a[i].y);

        g[S][i]=g[i][S]=min(a[i].x-,line-a[i].y),

        g[T][i]=g[i][T]=min(a[i].y-,row-a[i].x);

    for(int i=;i<=n;i++)

        for(int j=i;j<=n;j++)

            g[i][j]=g[j][i]=get_dis(a[i],a[j])/2.0;

    ans=inf;

    for(int i=;i<=n;i++)

        ans=min(ans,get_dis(a[i],(M){,})),

        ans=min(ans,get_dis(a[i],(M){row,line}));

    g[S][T]=g[T][S]=min(row-,line-);

}

void spfa(){

    for(int i=;i<=T;i++) vis[i]=,dis[i]=inf;

    unsigned short h=,t=;real dl;

    q[t]=S;dis[S]=;

    while(h!=t){

        int x=q[++h];vis[x]=;//少打个标记90变30

        for(int i=;i<=T;i++){

            if(x!=i&&(dl=max(dis[x],g[x][i]))<dis[i]){

                dis[i]=dl;

                if(!vis[i]){

                    vis[i]=;

                    q[++t]=i;

                }

            }

        }

    }

}

int main(){

    setfire(dis);

    init();

    mapping();

    spfa();

    ans=min(ans,dis[T]);

    printf("%.2lf",ans);

    return ;

}