Compilare: main.cpp: In function 'bool is_substring(int, int)': main.cpp:48:27: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 48 | for(int pos = sz; pos <= a[j].size(); pos++) { | ~~~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:71:26: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 71 | for(int j = 1; j <= a[i].size(); j++) { | ~~^~~~~~~~~~~~~~