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

#define all(x) (x).begin(), (x).end()
#define repeat(x) for(int taramtam = 0;taramtam<(x);taramtam++)

template<typename S, typename T> void semax(S &a, const T &b) {if (a<b) a = b;}
template<typename S, typename T> void semin(S &a, const T &b) {if (a>b) a = b;}

void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail>
void dbg_out(Head H, Tail... T) { cerr << ' ' << H;dbg_out(T...);}
#define debug(...) cerr << "(" #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)

const int INF = 1e9+100;
const int MOD = 1e9+7;

#define int long long
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename S>
void displayvec(vector<S> a){
    for (S thing:a){
        cout << thing << ' ';
    }
    cout << '\n';
}
template <typename S> 
void readvec(vector<S>& a){
    for (S& thing:a){
        cin>>thing;
    }
}

void solve(){
    int n, m;cin>>n>>m;
    vector<string> strs;
    vector<vector<int>> ha(m, vector<int>(26, 0));
    vector<int> prs = {0};
    for(int i = 0;i<n;i++){
        string s;cin>>s;
        strs.push_back(s);
        for(int j = 0;j<m;j++){
            ha[j][s[j]-'a']++;
        }
        int locres=0;
        for(int j = 0;j<m;j++){
            locres+=*max_element(all(ha[j]));
        }

        prs.push_back(locres);
    }
    int res =0;
    vector<vector<int>> ha2(m, vector<int>(26, 0));
    for(int i = 0;i<n;i++){
        string s=strs[n-i-1];
        for(int j = 0;j<m;j++){
            ha2[j][s[j]-'a']++;
        }
        int locres=0;
        for(int j = 0;j<m;j++){
            locres+=*max_element(all(ha2[j]));
        }
        res=max(res, locres+prs[n-i-1]);
    }
    cout << res << '\n';

}







signed main() {
    ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
    //freopen("compin.txt", "r", stdin);
	//freopen("compout.txt", "w", stdout);
    int TestCase = 1;
    cin >> TestCase;
    while(TestCase--) solve();
}