#include <bits/stdc++.h>
using namespace std;

const int MAX = 2e5;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(NULL), cout.tie(NULL);
    
    int t;
    cin >> t;
    
    while (t--)
    {
        int n, m;
        cin >> n >> m;
        
        vector< vector< vector<int> > > A(26, vector< vector<int> >(n + 1, vector<int>(m)));
        
        for (int i = 1; i <= n; i++)
        {
            string s;
            cin >> s;
            
            for (int j = 0; j < 26; j++)
                for (int k = 0; k < m; k++)
                    A[j][i][k] = A[j][i - 1][k] + (s[k] - 'a' == j);
        }
        
        int res = 0;
        
        for (int i = 1; i < n; i++)
        {
            int curr = 0;
            
            for (int k = 0; k < m; k++)
            {
                int max1 = 0, max2 = 0;
                
                for (int j = 0; j < 26; j++)
                {
                    max1 = max(max1, A[j][i][k]);
                    max2 = max(max2, A[j][n][k] - A[j][i][k]);
                }
                
                curr += max1 + max2;
            }
            
            res = max(res, curr);
        }
        
        cout << res << "\n";
    }
    
    return 0;
}