Compilare: main.cpp: In function 'void solve4()': main.cpp:34:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for (int i = 0; i < v[x].size(); i += 2) { | ~~^~~~~~~~~~~~~ main.cpp:40:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 40 | for (int i = 0; i < v[1].size(); i+=2) { | ~~^~~~~~~~~~~~~