#include <iostream>
#include <cstdlib>
using namespace std;
int main(){int n,m;cin>>n;long double x,y,a,b,c=0,d=0,e=0,f=0,g=0,h;
for(m=0;m<n;m++){cin>>x>>y;c+=x;d+=y;g+=x*y;e+=x*x;f+=y*y;}a=(n*g-c*d)/(n*e-c*c);
b=(e*d-c*g)/(n*e-c*c);h=f+a*a*e+n*b*b+2*a*b*c-2*a*g-2*b*d;cout<<h;}