#include <bits/stdc++.h> using namespace std; typedef long double ldouble; int n,i; ldouble x[100100],y[100100]; ldouble sqr(ldouble x) { return x*x; } ldouble calc(ldouble a, ldouble b) { ldouble r=0; for (int i=0; i<n; i++) r+=sqr(a*x[i]+b-y[i]); return r; } ldouble solve2(ldouble a) { ldouble r=1e6,l=-r; while (l<r-1e-7) { ldouble h1=(l+l+r)/3.,s1=calc(a,h1); ldouble h2=(l+r+r)/3.,s2=calc(a,h2); if (s1<s2) r=h2; else l=h1; } return calc(a,(l+r)*0.5); } ldouble solve(ldouble l, ldouble r) { while (l<r-1e-7) { ldouble h1=(l+l+r)/3.,s1=solve2(h1); ldouble h2=(l+r+r)/3.,s2=solve2(h2); if (s1<s2) r=h2; else l=h1; } return solve2((l+r)*0.5); } int main() { cin>>n; if (n>1000) for(;;); for (i=0; i<n; i++) cin>>x[i]>>y[i]; cout<<setprecision(8)<<fixed; cout<<min(solve(-1e6,0),solve(0,1e6))<<'\n'; return 0; }