#include <bits/stdc++.h>
using namespace std;
typedef long double ldouble;
int n,i;
double x[111],y[111];
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() {
  scanf("%d",&n);
  for (i=0; i<n; i++) scanf("%lf%lf",&x[i],&y[i]);
  printf("%.8f\n",double(min(solve(-1e6,0),solve(0,1e6))));
  return 0;
}