func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   template <typename T, typename U>   ostream& operator<<(ostream& os, const pair<T, U>& p) {     os << p.first <<     << p.second;     return os;   }   template <typename T>   ostream& operator<<(ostream& os, const vector<T>& vec) {     for (int i = 0; i < vec.size(); i++) {       os << vec[i] << (i + 1 == vec.size() ?    :    );     }     return os;   }   void solve() {     int h, w;     cin >> h >> w;     vector<vector<int>> ans;     vector<vector<int>> s(h, vector<int>(w));     for (int i = 0; (i) < (int)(h); (i)++) {       string t;       cin >> t;       for (int j = 0; (j) < (int)(w); (j)++) {         s[i][j] = t[j] -  0 ;       }     }     auto exc = [&](int y0, int x0, int y1, int x1, int y2, int x2) {       s[y0][x0] = s[y0][x0] ^ 1;       s[y1][x1] = s[y1][x1] ^ 1;       s[y2][x2] = s[y2][x2] ^ 1;       vector<int> r = {y0 + 1, x0 + 1, y1 + 1, x1 + 1, y2 + 1, x2 + 1};       ans.push_back(r);     };     auto exc2 = [&](int topy, int leftx, int no_use_y, int no_use_x) {       vector<int> r;       for (int i = topy; i < topy + 2; i++) {         for (int j = leftx; j < leftx + 2; j++) {           if (i != no_use_y || j != no_use_x) {             r.push_back(i + 1);             r.push_back(j + 1);           }         }       }       s[r[0] - 1][r[1] - 1] ^= 1;       s[r[2] - 1][r[3] - 1] ^= 1;       s[r[4] - 1][r[5] - 1] ^= 1;       ans.push_back(r);     };     if ((h & 1) && (w & 1)) {       if (s[h - 1][w - 1] == 1) {         exc(h - 1, w - 1, h - 2, w - 1, h - 1, w - 2);       }       for (int i = 0; i < h - 1; i += 2) {         if (s[i][w - 1] == 1) {           if (s[i + 1][w - 1] == 1) {             exc(i, w - 1, i + 1, w - 1, i, w - 2);           } else {             exc(i, w - 1, i, w - 2, i + 1, w - 2);           }         } else {           if (s[i + 1][w - 1] == 1) {             exc(i + 1, w - 1, i, w - 2, i + 1, w - 2);           }         }       }       for (int i = 0; i < w - 1; i += 2) {         if (s[h - 1][i] == 1) {           if (s[h - 1][i + 1] == 1) {             exc(h - 1, i, h - 1, i + 1, h - 2, i);           } else {             exc(h - 1, i, h - 2, i, h - 2, i + 1);           }         } else {           if (s[h - 1][i + 1] == 1) {             exc(h - 1, i + 1, h - 2, i, h - 2, i + 1);           }         }       }     } else if (h & 1) {       for (int i = 0; i < w - 1; i += 2) {         if (s[h - 1][i] == 1) {           if (s[h - 1][i + 1] == 1) {             exc(h - 1, i, h - 1, i + 1, h - 2, i);           } else {             exc(h - 1, i, h - 2, i, h - 2, i + 1);           }         } else {           if (s[h - 1][i + 1] == 1) {             exc(h - 1, i + 1, h - 2, i, h - 2, i + 1);           }         }       }     } else if (w & 1) {       for (int i = 0; i < h - 1; i += 2) {         if (s[i][w - 1] == 1) {           if (s[i + 1][w - 1] == 1) {             exc(i, w - 1, i + 1, w - 1, i, w - 2);           } else {             exc(i, w - 1, i, w - 2, i + 1, w - 2);           }         } else {           if (s[i + 1][w - 1] == 1) {             exc(i + 1, w - 1, i, w - 2, i + 1, w - 2);           }         }       }     }     if (h & 1) h--;     if (w & 1) w--;     for (int i = 0; i < h; i += 2) {       for (int j = 0; j < w; j += 2) {         while (true) {           int c = 0;           for (int ii = i; ii < i + 2; ii++) {             for (int jj = j; jj < j + 2; jj++) {               c += (s[ii][jj] == 1);             }           }           if (c == 0) {             break;           } else if (c == 1 || c == 3) {             [&]() {               for (int ii = i; ii < i + 2; ii++) {                 for (int jj = j; jj < j + 2; jj++) {                   if (s[ii][jj] == 0) {                     exc2(i, j, ii, jj);                     return;                   }                 }               }             }();           } else if (c == 2 || c == 4) {             [&]() {               for (int ii = i; ii < i + 2; ii++) {                 for (int jj = j; jj < j + 2; jj++) {                   if (s[ii][jj] == 1) {                     exc2(i, j, ii, jj);                     return;                   }                 }               }             }();           }         }       }     }     cout << ans.size() <<   n ;     for (int i = 0; (i) < (int)(ans.size()); (i)++) {       cout << ans[i] <<   n ;     }   }   int main() {     cin.tie(nullptr);     ios::sync_with_stdio(false);     int t;     cin >> t;     while (t--) {       solve();     }     return 0;   }   