Compilare: main.cpp: In function 'bool isValid(std::string)': main.cpp:24:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 24 | for(int i = 0 ; i < s.length();i++){ | ~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:50:13: warning: unused variable 'nrMatch' [-Wunused-variable] 50 | int i=1,nrMatch=0; | ^~~~~~~