#include<bits/stdc++.h>
using namespace std;
using lf=__float128;

template<typename DOUBLE>
struct Simplex_Steep {
  using VD = vector<DOUBLE>;
  using VVD = vector<VD>;
  using VI = vector<int>;
  const DOUBLE EPS = 1e-6;
  int m, n;
  VI B, N;
  VVD D;

  int iteration_cnt = 0;

  Simplex_Steep(const VVD &A, const VD &b, const VD &c) :
    m(b.size()), n(c.size()), B(m), N(n+1), D(m+2, VD(n+2)) {
    for (int i = 0; i < m; i++) for (int j = 0; j < n; j++) D[i][j] = A[i][j];
    for (int i = 0; i < m; i++) { B[i] = n+i; D[i][n] = -1; D[i][n+1] = b[i]; }
    for (int j = 0; j < n; j++) { N[j] = j; D[m][j] = -c[j]; }
    N[n] = -1; D[m+1][n] = 1;
  }

  void Pivot(int r, int s) {
    for (int i = 0; i < m+2; i++) if (i != r)
      for (int j = 0; j < n+2; j++) if (j != s)
        D[i][j] -= D[r][j] * D[i][s] / D[r][s];
    for (int j = 0; j < n+2; j++) if (j != s) D[r][j] /= D[r][s];
    for (int i = 0; i < m+2; i++) if (i != r) D[i][s] /= -D[r][s];
    D[r][s] = 1.0 / D[r][s];
    swap(B[r], N[s]);
  }

  bool Simplex(int phase) {
    int x = phase == 1 ? m+1 : m;
    while (true) {
      ++iteration_cnt;
      int s = -1;
      DOUBLE c_val = -1;
      for (int j = 0; j <= n; j++) {
        if (phase == 2 && N[j] == -1) continue;
        DOUBLE norm_sq = 0;
        for(int k=0; k<=m;++k){ norm_sq+= D[k][j]*D[k][j];}
        if(norm_sq < EPS) norm_sq = EPS; // stop division by 0
        DOUBLE c_val_j = D[x][j] / sqrtl(norm_sq);
        if (s == -1 || c_val_j < c_val  || (c_val == c_val_j && N[j] < N[s])){
            s = j; c_val = c_val_j;
        }
      }
      if (D[x][s] >= -EPS) return true;
      int r = -1;
      for (int i = 0; i < m; i++) {
        if (D[i][s] <= EPS) continue;
        if (r == -1 || D[i][n+1] / D[i][s] < D[r][n+1] / D[r][s] ||
            (D[i][n+1] / D[i][s] == D[r][n+1] / D[r][s] && B[i] < B[r])) r = i;
      }
      if (r == -1) return false;
      Pivot(r, s);
    }
  }

  DOUBLE solve(VD &x) {
    int r = 0;
    for (int i = 1; i < m; i++) if (D[i][n+1] < D[r][n+1]) r = i;
    if (D[r][n+1] <= -EPS) {
      Pivot(r, n);
      if (!Simplex(1) || D[m+1][n+1] < -EPS) return -numeric_limits<DOUBLE>::infinity();
      for (int i = 0; i < m; i++) if (B[i] == -1) {
        int s = -1;
        for (int j = 0; j <= n; j++)
          if (s == -1 || D[i][j] < D[i][s] || (D[i][j] == D[i][s] && N[j] < N[s])) s = j;
        Pivot(i, s);
      }
    }
    if (!Simplex(2)) return numeric_limits<DOUBLE>::infinity();
    x = VD(n);
    for (int i = 0; i < m; i++) if (B[i] < n) x[B[i]] = D[i][n+1];
    //cerr << "Steepest edge iterations: " << iteration_cnt << "\n";
    return D[m][n+1];
  }
};

int main()
{
    cin.tie(0)->sync_with_stdio(0);
	// simplex with 7 dimensions, each being r, a1, a2, b1, b2, c1, c2 (1 and 2 exist due to bypassing nonnegativity constraints)
    // max -r
    // s.t. -r - a1*x^2 + a2*x^2 - b1*x + b2*x - c1 + c2 <= -y
    //      -r + a1*x^2 - a2*x^2 + b1*x - b2*x + c1 - c2 <= y
    vector<lf>c{-1,0,0,0,0,0,0};
    int q;cin>>q;
    while(q--)
    {
        vector<vector<lf>>A;
        vector<lf>B;
        vector<lf>x;
        int n;cin>>n;
        while(n--)
        {
            long long x,y;
            cin>>x>>y;
            B.push_back(-y);
            A.push_back({-1,-x*x,x*x,-x,x,-1,1});
            B.push_back(y);
            A.push_back({-1,x*x,-x*x,x,-x,1,-1});
        }
        lf ans=Simplex_Steep<lf>(A,B,c).solve(x);
        cout<<setprecision(7)<<fixed<<abs(double(ans*ans))<<"\n";
    }
}