#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
using ll = long long;

void solve() {
    ll n, m;
    cin >> n >> m;
    vector<string> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i];
    }
    vector<ll> mp(n);
    for(int j = 0; j < m; j++) {
        vector<ll> pre(26), suf(26);
        for(int i = 0; i < n; i++) {
            suf[v[i][j] - 'a'] += 1;
        }
        for(int i = 0; i < n; i++) {
            suf[v[i][j] - 'a'] -= 1;
            pre[v[i][j] - 'a'] += 1;
            mp[i] += *max_element(pre.begin(), pre.end()) + *max_element(suf.begin(), suf.end());
        }
    }
    cout << *max_element(mp.begin(), mp.end()) << endl;
    return;
}

int main() {
    ios::sync_with_stdio(false); cin.tie(0);
    int tc = 1;
    cin >> tc;
    for (int t = 1; t <= tc; t++) {
        // cout << "Case " << t << ": ";
        solve();
    }
    return 0;
}