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

inline void solve()
{
    int n, m;
    cin >> n >> m;

    vector<string> S(n);
    for(auto& i : S ) cin >> i;

    vector< vector<int> > B(m, vector<int>(26,0) ), F(m, vector<int>(26, 0) );
    vector<int> bs(n);

    for(int i=n-1; i >= 0; --i){
        for(int k=0; k < m; ++k){
            B[k][ S[i][k] - 'a' ] ++;
            bs[i] += *max_element(B[k].begin(), B[k].end() );
        }
    }

    int ans = bs[0];
    for(int i=0; i < n; ++i){
        int cur = 0;
        for(int k=0; k < m; ++k){
            F[k][ S[i][k] - 'a' ] ++;
            cur += *max_element(F[k].begin(), F[k].end() );
        }
        ans = max(ans, cur + ( i+1 < n ? bs[i+1] : 0 ) );
    }
    cout << ans << "\n";
}

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