Compilare: main.cpp: In function 'int main()': main.cpp:29:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 29 | for(int j=0; j<elem[i].size(); j++) | ~^~~~~~~~~~~~~~~ main.cpp:33:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 33 | if(j!=elem[i].size()-1) | ~^~~~~~~~~~~~~~~~~~