#include <bits/stdc++.h>
#define pb push_back
#define pf push_front
#define pi 2*acos(0.0)
#define f first
#define s second
#define inf INT_MAX
#define MXN 500001
#define endl "\n"
#define eps 1e-6
#define mod 1000000007
#define all(x) x.begin(), x.end()
#define rev(x) x.rbegin(), x.rend()
#define spc(x) cout << fixed << setprecision(x)
#define fastio {ios_base::sync_with_stdio(false); cin.tie(NULL);}
#define test ll t; cin >> t; while (t--)

typedef long long ll;
using namespace std;

void solve()
{
    ll n, m;
    cin >> n >> m;

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

    if(n == 1) {
        cout << m << endl;
        return;
    }

    ll ans = 0;
    vector<vector<ll>> pref(n, vector<ll>(m, 0));
    vector<vector<ll>> suff(n, vector<ll>(m, 0));
    
    for(int i = 0; i < m; i++) {
        map<char, ll> mp1, mpp1;
        ll mxx = 0, mxx1 = 0;
        
        for(int j = 0; j < n; j++) {
            mp1[v[j][i]]++;
            mxx = max(mxx, mp1[v[j][i]]);
            pref[j][i] = mxx;
        }

        for(int j = n - 1; j >= 0; j--) {
            mpp1[v[j][i]]++;
            mxx1 = max(mxx1, mpp1[v[j][i]]);
            suff[j][i] = mxx1;
        }
    }
    
     
    for(int i=0;i<n;i++){
      ll tot=0;

         for(int j=0;j<m;j++){
          
          if(i<n-1){
          tot+=pref[i][j]+suff[i+1][j];
          }
          else{
               tot+=pref[i][j];
          }
      }
      ans=max(ans,tot);
    }
    
    cout << ans << endl;
}

int32_t main()
{
    fastio
    int t = 1;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}