/in/foo.cc: In function 'int main(int, char**)':
/in/foo.cc:103:37: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |         for (int row1 = 0; row1 + 1 < rowc.size(); row1++) {
      |                            ~~~~~~~~~^~~~~~~~~~~~~
/in/foo.cc:113:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  113 |           for (int row1 = 0; row1 < rowc.size(); row1++) {
      |                              ~~~~~^~~~~~~~~~~~~
/in/foo.cc:49:7: warning: unused variable 'brk' [-Wunused-variable]
   49 |   int brk = 0;
      |       ^~~
/in/foo.cc:66:10: warning: unused variable 'ec' [-Wunused-variable]
   66 |     auto ec = scanf("%d%d%d%d", &n, &m, &r, &c);
      |          ^~