Compilare: main.cpp: In function 'int main()': main.cpp:40:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | for(int i=0;i<used.size()-1 and valid;++i) | ~^~~~~~~~~~~~~~ main.cpp:41:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 41 | for(int j=i+1;j<used.size() and valid;++j) | ~^~~~~~~~~~~~ main.cpp:52:22: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 52 | if(cate[2].size()==n) | ~~~~~~~~~~~~~~^~~