Pulkit is really good at maths. Recently, he came to know about a problem on matrices. Amazed by the problem he got, he asked Ashish the same problem. Ashish also being good at maths solved the problem within 5 minutes. Now, its your time to solve the problem.

You will be given n*m binary matrix. You need to tell if it is possible to delete a column such that after deleting that column, rows of the matrix will be unique. If yes than print "Yes" else print "No". 

[Input]
First line contains an integer t denoting no.of test cases. 
Next line contains 2 integers n and m denoting no.of rows and columns.
Next n line contains binary string of length m each.

[Output]
For each test case output "Yes" or "No".

[Constraints]
1 ≤ t ≤ 100
1 ≤ n ≤ 1000
2 ≤ m ≤ 1000

SAMPLE INPUT
2
3 3
101
000
100
2 2
11
11

SAMPLE OUTPUT
Yes
No
for i in range(input()):
	l=[int(x) for x in raw_input().split()]
	l1=[]
	l2=[]
	for j in range(l[0]):
		a=input()
		l1.append(a)
	for k in range(0,len(l1)):
		if(l1[k] not in l2):
			l2.append(l1[k])
	if(len(l1)==len(l2)):
		print('Yes')
	else:
		print('No')