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
t = int(raw_input())
for i in range(t):
	x, y = raw_input().split()
	x = int(x)
	l = []
	for j in range(x):
		l.append(raw_input())
	l.sort()
	flag = True
	for j in range(x-1):
		if(l[j] == l[j+1]):
			flag = False
			break
	if flag:
		print("Yes")
	else:
		print("No")