Compilare: main.cpp: In function 'int check(int)': main.cpp:15:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 15 | for (int j=0; j<s[i].size(); ++j) | ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:41:10: warning: unused variable 'j' [-Wunused-variable] 41 | int i,j; | ^