Compilare: main.cpp: In function 'void back()': main.cpp:15:17: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare] 15 | if (v.size()==n) | ~~~~~~~~^~~ main.cpp:17:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 17 | for (int i = 0; i < v.size(); i++) | ~~^~~~~~~~~~ main.cpp:25:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 25 | for (int j = 0; j < v.size(); j++) | ~~^~~~~~~~~~