#include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define f first 
#define s second 
using namespace std;

int main(){
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);

    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int t;
    cin >> t;
    while (t--){
        ll n, m, ans = 0;
        cin >> n >> m;
        string s[n];
        ll a[m][26], v[n][m];
        for (int i = 0; i < m; i++){
          for (int j = 0; j < 26; j++){
            a[i][j] = 0;
          }
        }
        ll f = 0;
        for (int i = 0; i < n; i++){
          cin >> s[i];
          for (int j = 0; j < m; j++){
            a[j][s[i][j] - 97]++;
            ll mx  = 0;
            for (int k = 0; k < 26; k++){
              mx = max(mx, a[j][k]);
            }
            v[i][j] = mx;
          }
          if (i == 0) continue;
          if (!f) ans = 0;
          bool ok = true;
          for (int j = 0; j < m; j++){
            if (v[i - 1][j] != v[i][j]){
              ok = false;
              break;
            }
          }
          if (ok && f == 0){
            for (int j = 0; j < m; j++){
              ans += v[i - 1][j];
              for (int k = 0; k < 26; k++){
                a[j][k] = 0;
              }
            }
            for (int j = 0; j < m; j++){
              a[j][s[i][j] - 97]++;
              v[i][j] = 1;
            }
            f++;
          }
        }
        for (int i = 0; i < m; i++){
          ans += v[n - 1][i];
        }
        if (f == 0){
          ans = 0;
          for (int i = 0; i < m; i++){
            ans += min(n, v[n - 1][i] + 1);
          }
        }
        cout << ans << endl;
    }
}