#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main()
{
    double ans;
    ll i,n,x,y,dist,maxi=0,mini=1000000000000000,a[100010],b[100010] ;

    cin>>n;
    cin>>x>>y;
    for(i=0;i<n;i++)
    {
        cin>>a[i]>>b[i];
    }
    for(i=0;i<n;i++)
    {
        dist=((a[i]-x)*(a[i]-x))+((b[i]-y)*(b[i]-y));
        if(dist>maxi)
        {
        //  bigx=a[i];
        //  bigy=b[i];
            maxi=dist;
        }
        if(dist<mini)
        {
        //  smallx=a[i];
        //  smally=b[i];
            mini=dist;
        }
    }
    //cout<<maxi<<" "<<mini<<endl;
    ans=(double)((double)(22*(maxi-mini))/(double)7);
//  cout<<ans;
    //cout<<(double)ans/(double)7;
    cout << fixed << setprecision(10) << ans << endl;
    return 0;
}