#include <bits/stdc++.h>

using namespace std;

void solve(int cs) {
  int n, m;
  cin >> n >> m;
  vector<vector<vector<int>>> f(n, vector<vector<int>>(m, vector<int>(26, 0)));
  for (int i = 0; i < n; i++) {
    string s; cin >> s;
    for (int j = 0; j < m; j++) {
      f[i][j][s[j] - 'a'] += 1;
    }
    if (i) {
      for (int j = 0; j < m; j++) {
        for (int k = 0; k < 26; k++) {
          f[i][j][k] += f[i - 1][j][k];
        }
      }
    }
  }  
  int ans = 0;
  for (int j = 0; j < m; j++) {
    ans += *max_element(f.back()[j].begin(), f.back()[j].end());
  }
  for (int i = 0; i < n; i++) {
    int left = 0;
    for (int j = 0; j < m; j++) {
      int mx = 0;
      for (int k = 0; k < 26; k++) {
        mx = max(mx, f[i][j][k]);
      }
      left += mx;
    }
    int right = 0;
    for (int j = 0; j < m; j++) {
      int mx = 0;
      for (int k = 0; k < 26; k++) {
        mx = max(mx, f.back()[j][k] - f[i][j][k]);
      }
      right += mx;
    }
    ans = max(ans, left + right);
  }
  cout << ans << "\n";
}

int32_t main() {
  ios::sync_with_stdio(!cin.tie(0));
  int t = 1;
  cin >> t;
  for (int i = 1; i <= t; ++i) {
    solve(i);
  }
  return 0;
}