import math
import sys
for m in range(int(input())):
n=int(input())
ax=[]
ay=[]
for i in range(2*n):
x,y=map(int,input().split())
if(x==0):
ay.append(abs(y))
if(y==0):
ax.append(abs(x))
ax.sort()
ay.sort()
ans=0
for i in range(n):
ans+=(math.sqrt((ax[i]**2) + (ay[i]**2)))
print(ans)
1665D - GCD Guess | 29A - Spit Problem |
1097B - Petr and a Combination Lock | 92A - Chips |
1665B - Array Cloning Technique | 1665A - GCD vs LCM |
118D - Caesar's Legions | 1598A - Computer Game |
1605A - AM Deviation | 1461A - String Generation |
1585B - Array Eversion | 1661C - Water the Trees |
1459A - Red-Blue Shuffle | 1661B - Getting Zero |
1661A - Array Balancing | 1649B - Game of Ball Passing |
572A - Arrays | 1455A - Strange Functions |
1566B - MIN-MEX Cut | 678C - Joty and Chocolate |
1352E - Special Elements | 1520E - Arranging The Sheep |
1157E - Minimum Array | 1661D - Progressions Covering |
262A - Roma and Lucky Numbers | 1634B - Fortune Telling |
1358A - Park Lighting | 253C - Text Editor |
365B - The Fibonacci Segment | 75A - Life Without Zeros |