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(0,t):
    m=raw_input()
    m=m.split(" ")
    m=map(int,m)
    n=m[1]
    m=m[0]
    arr=[]
    r=0
    for j in range(0,m):
        a=raw_input()
        a=a.split(" ")
        a=map(int,a)
        arr.append(a)
    for x in arr:
    	if arr.count(x)>1:
    		r=1
    		break
    if r==1:
    	print 'No'
    else:
    	print 'Yes'