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
import sys

t=input()

while t>0:
    s=sys.stdin.readline().strip().split()
    s=map(int,s)
    n,m=s
    tm=n
    l=[]
    while tm>0:
        l.append(sys.stdin.readline().strip())
        tm=tm-1
    for c in xrange(0,m):
        d={}
        flg=0
        for r in l:
            cd=r[0:c]+r[c+1:]
            if cd in d:
               flg=1
               break
            else:
                d[cd]=1
        if flg==0:
            #print "Yes"
            break
    if flg==0:
        print "Yes"
    else:
        print "No"
    t=t-1