Compilare: user.cpp: In function ‘long long int substr_count(std::__cxx11::string, std::__cxx11::string)’: user.cpp:17:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); ++i) { ~~^~~~~~~~~~ user.cpp:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < a.size(); ++i) { ~~^~~~~~~~~~ user.cpp:26:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < b.size(); ++j) { ~~^~~~~~~~~~ user.cpp:37:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < b.size(); ++i) { ~~^~~~~~~~~~