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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int Tc;
    cin >> Tc;

    while (Tc--) {
        int N, M;
        cin >> N >> M;

        vector<string> rounds(N);
        for (int i = 0; i < N; ++i) {
            cin >> rounds[i];
        }

        vector<vector<int>> prefix(M, vector<int>(N + 1, 0));
        vector<vector<int>> suffix(M, vector<int>(N + 1, 0));

        for (int j = 0; j < M; ++j) {
            vector<int> freq(26, 0);
            for (int i = 0; i < N; ++i) {
                char c = rounds[i][j];
                freq[c - 'a']++;
                int current_max = *max_element(freq.begin(), freq.end());
                prefix[j][i + 1] = current_max;
            }

            fill(freq.begin(), freq.end(), 0);
            for (int i = N - 1; i >= 0; --i) {
                char c = rounds[i][j];
                freq[c - 'a']++;
                int current_max = *max_element(freq.begin(), freq.end());
                suffix[j][i] = current_max;
            }
        }

        vector<int> sum_prefix(N + 1, 0);
        vector<int> sum_suffix(N + 1, 0);

        for (int j = 0; j < M; ++j) {
            for (int k = 0; k <= N; ++k) {
                sum_prefix[k] += prefix[j][k];
                sum_suffix[k] += suffix[j][k];
            }
        }

        int ans = 0;
        for (int k = 0; k <= N; ++k) {
            ans = max(ans, sum_prefix[k] + sum_suffix[k]);
        }

        cout << ans << '\n';
    }

    return 0;
}