Compilare: main.cpp: In function 'bool pos(std::vector<char>, int)': main.cpp:14:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k == ss.size() && s.size() == 0) return 1; ~~^~~~~~~~~~~~ main.cpp:15:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(k >= ss.size() && s.size() > 0) return 0; ~~^~~~~~~~~~~~ main.cpp:23:31: warning: array subscript has type 'char' [-Wchar-subscripts] else for(auto c : str[s[0]]) { ^ main.cpp: In function 'int main()': main.cpp:52:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(; i < a.size(); i += 2) { ~~^~~~~~~~~~