Compilare: main.cpp: In function 'bool is_subsequence(std::string, std::string)': main.cpp:21:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 21 | for (int i = 0; i < s2.size(); i++) { | ~~^~~~~~~~~~~ main.cpp:26:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 26 | return j == s1.size(); | ~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:44:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 44 | for (int i = 0; i < strings.size(); i++) | ~~^~~~~~~~~~~~~~~~ main.cpp:45:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::__cxx11::basic_string<char> >::size_type' {aka 'long unsigned int'} [-Wsign-compare] 45 | for (int j = 0; j < strings.size(); j++) | ~~^~~~~~~~~~~~~~~~