#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;
}
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