Compilare: main.cpp: In function 'void test_1()': main.cpp:34:37: warning: comparison of integer expressions of different signedness: 'std::size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 34 | ok &= arr[i].count()==x/2; | ~~~~~~~~~~~~~~^~~~~ main.cpp: In lambda function: main.cpp:143:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 143 | for (int i = 0; i < s0.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:129:21: warning: unused variable 'first_col' [-Wunused-variable] 129 | int first_col = 0; | ^~~~~~~~~