#include<bits/stdc++.h>
#include<atcoder/all>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define Yes(n) cout << ((n) ? "Yes" : "No"  ) << endl
#define print(var) std::cout<<#var<<"="<<(var)<<std::endl
#define all(a) (a).begin(), (a).end()
#define vi vector<int>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define ll long long
#define vll vector<ll>
#define vvll vector<vll>
#define vvvll vector<vvll>
#define vmi vector<mint>
#define vvmi vector<vmi>
#define vvvmi vector<vvmi>
#define vs vector<string>
#define pii pair<int,int>
#define vpii vector<pii>
#define vvpii vector<vpii>
#define bit(x,i)(((x)>>(i))&1)
#define inf (1<<30)
#define INF (1ll<<60)
template<typename T> inline bool chmax(T &a, T b) { return ((a < b) ? (a = b, true) : (false)); }
template<typename T> inline bool chmin(T &a, T b) { return ((a > b) ? (a = b, true) : (false)); }
template<class T, class F> T nibutan(T ok, T ng, const F &f){while(abs(ok-ng)>1){T mid = (ok+ng)/2;(f(mid)?ok:ng) = mid;}return ok;}
template<class T> vector<T> digit(T x){vector<T> res; while(x>0){res.push_back(x%10); x/=10;} return res;}

#ifdef LOCAL
#include "../../cpp-dump/dump.hpp"
#else
#define cpp_dump
#endif

static uint32_t xor128(void){
    static uint32_t x=123456789,y=362436069,z=521288629,w=88675123;
    uint32_t t;
    t=(x^(x<<11));x=y;y=z;z=w; return( w=(w^(w>>19))^(t^(t>>8)) );
}
int randrange(int a){return (uint64_t(xor128()) * a >> 32); }
double randDouble(double a,double b){return a+(b-a)*xor128()/(double)ULONG_MAX;}

inline double get_time() {
    using namespace std::chrono;
    return duration_cast<milliseconds>(system_clock::now().time_since_epoch()).count();
}
double start_time = get_time();

struct IO{
    int n;
    vll a,b;
    IO(){}
    void input(){
        cin >> n;
        a.resize(n);
        b.resize(n);
        for(int i=0;i<n;i++){
            cin >> a[i] >> b[i];
        }
    }
};

struct State{
    int n;
    unordered_set<int> used;
    vi seq;
    pair<double,double> now;
    State(IO& io) : n(io.n){
    }

    void add_back(int i, IO& io){
        if(used.find(i) != used.end()){
            cerr << "error : " << i << " is already used" << endl;
            return;
        }
        now.first = (now.first + io.a[i])/2;
        now.second = (now.second + io.b[i])/2;

        seq.push_back(i);
        used.insert(i);
    }

    void swap(int i, int j, IO& io){
        if(i>=seq.size()){
            cerr << "seq size is " << seq.size() << " but i is " << i << endl;
            return;
        }
        if(used.find(j) != used.end()){
            cerr << "error : " << j << " is already used" << endl;
            return;
        }

        now.first = now.first - io.a[seq[i]]*pow(0.5,seq.size()-i-1);
        now.second = now.second - io.b[seq[i]]*pow(0.5,seq.size()-i-1);
        seq[i] = j;
        now.first = now.first + io.a[j]*pow(0.5,seq.size()-i-1);
        now.second = now.second + io.b[j]*pow(0.5,seq.size()-i-1);

        seq[i] = j;
        used.insert(j);
        used.erase(seq[i]);
    }

    double get_score(){
        double diff1 = now.first - 500000000000000000ll;
        double diff2 = now.second - 500000000000000000ll;
        double score = diff1*diff1 + diff2*diff2;
        return score;
    }

    void update(IO& io){
        int coin = randrange(10);
        if(coin < 2 && seq.size() < n-1){
            int i;
            do{
                i = randrange(n-1)+1;
            }while(used.find(i) != used.end());
            
            add_back(i,io);
        }
        else{
            int i,j;
            i = randrange(seq.size());
            do{
                j = randrange(n-1)+1;
            }while(used.find(j) != used.end());

            swap(i,j,io);
        }
    }
};

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    IO io;
    io.input();

    State now_state(io);
    double now_score = now_state.get_score();
    while(get_time() - start_time < 900){
        State state = now_state;
        state.update(io);
        if(chmin(now_score, state.get_score())){
            swap(now_state, state);
            cout << now_score << endl;
        }
    }
}