#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long int
#define endl '\n'
typedef tree<ll, null_type, less<ll>, rb_tree_tag, tree_order_statistics_node_update> pbds; // find_by_order, order_of_key
#define all(v) v.begin(), v.end()
#define yes cout << "YES" << endl        
#define no cout << "NO" << endl          
#define M 1000000007                     
#define lcm(a, b) a *b / gcd(a, b)       
#define memz(a) memset(a, 0, sizeof(a))  
#define memn(a) memset(a, -1, sizeof(a)) 
ll dx[]={1,0,-1,0,1,-1,-1,1};
ll dy[]={0,1,0,-1,1,1,-1,-1};

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    ll tst;
    cin>>tst;
    for(ll test=1;test<=tst;test++)
    {
        //cout<<"Case "<<test<<": ";
        ll n,m;
        cin>>n>>m;
        map<char,ll>mp[m];
        string in[n];
        ll mx[m]={0};
        ll fmx[n]={0};
        for(int i=0;i<n;i++)
        {
            cin>>in[i];
            ll c=0;
            for(int j=0;j<m;j++)
            {
                mp[j][in[i][j]]++;
                mx[j]=max(mx[j],mp[j][in[i][j]]);
                c+=mx[j];
            }
            fmx[i]=c;
        }
        map<char,ll>mp1[m];
        ll mx1[m]={0};
        ll bmx[n]={0};
        for(int i=n-1;i>=0;i--)
        {
            ll c=0;
            for(int j=0;j<m;j++)
            {
                mp1[j][in[i][j]]++;
                mx1[j]=max(mx1[j],mp1[j][in[i][j]]);
                c+=mx1[j];
            }
            bmx[i]=c;
        }
        ll ans=max(fmx[n-1],bmx[0]);
        for(int i=0;i<n-1;i++)
        {
            ans=max(ans,fmx[i]+bmx[i+1]);
        }
        cout<<ans<<endl;
        // cout<<ans<<endl;
        // for(int i=0;i<n;i++)cout<<fmx[i]<<" ";
        // cout<<endl;
        // for(int i=0;i<n;i++)cout<<bmx[i]<<" ";
    }
}