Compilare: main.cpp: In function 'int main()': main.cpp:18:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 18 | for(int j = 0; j < v[i].size(); j += 2) { | ~~^~~~~~~~~~~~~ main.cpp:24:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 24 | for(int i = 0; i < v[0].size(); i++) { | ~~^~~~~~~~~~~~~