Compilare: main.cpp: In function 'int Diff(std::__cxx11::string, std::__cxx11::string)': main.cpp:17:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= a.size(); ++ i ) ~~^~~~~~~~~~~ main.cpp:19:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= b.size(); ++ i ) ~~^~~~~~~~~~~ main.cpp:22:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i <= a.size(); ++ i ) { ~~^~~~~~~~~~~ main.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; j <= b.size(); ++ j ) { ~~^~~~~~~~~~~