#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#include<assert.h>
#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

int main(){
  int N, K, mp[120][120];

  int i, j, dp[120][120];
  int a;
  double res;

  assert( scanf("%d",&N)==1 );
  assert(0<=N && N<=20);
  while(N--){
    assert( scanf("%d",&K)==1 );
    assert( 2<=K && K<=100 );
    rep(i,K) rep(j,K) assert( scanf("%d",mp[i]+j)==1 ), assert( -2500<=mp[i][j] && mp[i][j]<=2500 );

    /* Let's use dynamic programming */
    dp[0][0] = 0;
    REP(i,1,K) dp[0][i] = dp[0][i-1] + mp[0][i];
    REP(i,1,K) dp[i][0] = dp[i-1][0] + mp[i][0];
    REP(i,1,K) REP(j,1,K){
      if(dp[i][j-1] > dp[i-1][j]) dp[i][j] = dp[i][j-1] + mp[i][j];
      else                        dp[i][j] = dp[i-1][j] + mp[i][j];
    }

    if(dp[K-1][K-1] < 0){ puts("Bad Judges"); continue; }
    res = dp[K-1][K-1] / (double)(2*K-3);
    printf("%.10f\n",res);
/*    {
      long double RES;
      RES = dp[K-1][K-1] / (long double)(2*K-3);
      printf("%.20Lf\n",RES);
    }*/
  }

  return 0;
}