#include <bits/stdc++.h>
#include <cmath>
#include <bitset>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
#define ll long long int
#define lld long double
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) ((a * b) / gcd(a, b))
#define pi acos(-1.00)
void evan(int t)
{
  ll n,m;cin>>n>>m;
  char a[n][m];
  for(int i=0;i<n;i++){
    for(int j=0;j<m;j++){
      cin>>a[i][j];
    }
  }
 vector<vector<vector<ll>>>v(n,vector<vector<ll>>(m,vector<ll>(26,0)));
 for(int j=0;j<m;j++){
  for(int i=0;i<n;i++){
    for(int k=0;k<26;k++){
        if(k==a[i][j]-'a'){
          if(i!=0)v[i][j][k]=v[i-1][j][k]+1;
          else v[i][j][k]=1;
        }
        else{
           if(i!=0) v[i][j][k]=v[i-1][j][k];
           else v[i][j][k]=0;
        }
    }
  }
}
ll ans=-1;
 for(int i=0;i<n;i++){
  ll temp=0;
  for(int j=0;j<m;j++){
    ll maxx1=-1;
      for(int k=0;k<26;k++){
          if(v[i][j][k]>maxx1)maxx1=v[i][j][k];
      }
      ll maxx2=-1;
      for(int k=0;k<26;k++){
        if(v[n-1][j][k]-v[i][j][k]>maxx2)maxx2=v[n-1][j][k]-v[i][j][k];
    }
    temp+=maxx1+maxx2;
  }
  ans=max(ans,temp);
 }
 cout<<ans<<"\n";

}
signed main()
{
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(nullptr);
  int t = 1;
  cin >> t;
  for (int i = 1; i <= t; i++)
  {
    evan(i);
  }
}