#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <cstring>
#include <set>
#include <map>
#include <ctime>
#include <unordered_map>
#include <stack>
using namespace std;

#define inf 2147483647
#define eps 0.0000000000001
#define pi 3.1415926535897932
#define mod 1000000007
#define LL long long
#define ULL unsigned long long
#define LD long double
#define ULD unsigned long double

const int N = 100005;

//  printf("Case #%d: ", ++T);
//  srand(time(NULL));
//  cout<<fixed<<setprecision(3)<<"\nExecution time="<<clock()/1000.0<<endl;
//  freopen("input.txt","r",stdin);
//  freopen("output.txt","w",stdout);

long long n, m, i, j, k, q, s, w, v, ans;
long double a[1010][2020];
long double b[1010][2020];

long double proc(int i, int j)
{
	if (i == n + 1)
		return 0;

	if (a[i][j * 2 - 1] == a[i][j * 2])
		return (proc(i + 1, j) + proc(i + 1, j + 1)) / 2 + a[i][j * 2];

	else
	{
		if (a[i][j * 2 - 1] < a[i][j * 2])
			return proc(i + 1, j) + a[i][j * 2 - 1];
		else
			return proc(i + 1, j + 1) + a[i][j * 2];
	}
}

int main()
{
	cin >> w;
	while (w--)
	{
		cin >> n;

		for (i = 1; i <= n; i++)
			for (j = 1; j <= 2 * i; j++)
				cin >> a[i][j];

		cout << fixed << setprecision(7);
		cout<<proc(1, 1)<<endl;
	}
	return 0;
}