//用二进制法枚举,用int 越界RE 改为long long ac
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <cstdlib>
#define MAX 200
using namespace std;
int N,Row;
char str[200][MAX];
char cstr[200][MAX];
int digit[200];
int Max;
int cmp(const void *a,const void *b)
{
return strcmp((char *)a,(char *)b);
}
void Initial()
{
memset(str,0,sizeof(str));
memset(cstr,0,sizeof(cstr));
Max = 0;
}
void Copy_deal()
{
for(int i = 0;i < Row;i++)
for(int k = 0;k < N;k++)
{
if(digit[k])
{
cstr[i][k] = '0';
continue;
}
cstr[i][k] = str[i][k];
}
}
void Subset_deal(long long s)
{
memset(digit,0,sizeof(digit));
int count = 0;
for(long long i = 0;i < N;i++)
if( s & (1<<i) )
{
// cout<<i<<" ";
digit[i] = 1;
count++;
}
// cout<<endl;
Copy_deal();
qsort(cstr,Row,sizeof(cstr[0]),cmp);
int flage = 1;
for(int i = 0;i < Row-1;i++)
if(strcmp(cstr[i],cstr[i+1]) == 0)
{
flage = 0;
break;
}
if(flage)
if(Max < count)
Max = count;
}
int main()
{
//freopen("in.in","r",stdin);
int test_case;
cin>>test_case;
while(test_case--)
{
cin>>N>>Row;
Initial();
for(int i = 0; i < Row;i++)
for(int j = 0;j < N;j++)
cin>>str[i][j];
for(long long i = 0;i < (1<<N);i++)
Subset_deal(i);
cout<<N-Max<<endl;
}
return 0;
}