Compilare: main.cpp: In function 'void bkt_comb(int, int)': main.cpp:146:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 146 | for (int i=c[step-1]+1; i<=lines.size()-k+step; i++) | ~^~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:188:32: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 188 | for (nr_queens=1; nr_queens<=lines.size(); nr_queens++) | ~~~~~~~~~^~~~~~~~~~~~~~