#include <bits/stdc++.h>   using namespace std;   mt19937 rnd(51);   const long long INF = 1e18;   signed main() {     ios::sync_with_stdio(0);     cin.tie(0);     long long t;     cin >> t;     while (t--) {       long long n, m;       cin >> n >> m;       vector<vector<long long>> a(n, vector<long long>(m)),           pr(n, vector<long long>(m));       vector<vector<long long>> mn(m, vector<long long>(m, INF));       for (long long i = 0; i < n; i++) {         for (long long j = 0; j < m; j++) {           char c;           cin >> c;           a[i][j] = c -  0 ;           pr[i][j] = a[i][j] + (j > 0 ? pr[i][j - 1] : 0);         }       }       long long anss = 1e18;       for (long long i = 0; i < n; i++) {         for (long long j = 0; j < m; j++) {           for (long long jj = j; jj < m; jj++) {             if (jj - j + 1 >= 4) {               if (i > 0)                 mn[j][jj] += (a[i - 1][j] ^ 1) + (a[i - 1][jj] ^ 1) +                              (pr[i - 1][jj - 1] - pr[i - 1][j]);               if (i - 4 >= 0) {                 long long add = 0;                 for (long long f = i - 3; f < i; f++) {                   add +=                       (a[f][j] ^ 1) + (a[f][jj] ^ 1) + (pr[f][jj - 1] - pr[f][j]);                 }                 mn[j][jj] =                     min(mn[j][jj],                         (jj - j - 1) - (pr[i - 4][jj - 1] - pr[i - 4][j]) + add);               }               anss = min(anss,                          mn[j][jj] + (jj - j - 1) - (pr[i][jj - 1] - pr[i][j]));             }           }         }       }       cout << anss << endl;     }     return 0;   }   