Compilare: user.cpp: In function ‘std::vector<int> transform(std::string)’: user.cpp:13:9: warning: unused variable ‘n’ [-Wunused-variable] int n = s.size(), a = s.size()-5, b = s.size()-1;; ^ user.cpp: In function ‘std::vector<int> product(std::vector<int>, int)’: user.cpp:31:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<A.size(); i++) { ^ user.cpp: In function ‘std::vector<int> diff(std::vector<int>, std::vector<int>)’: user.cpp:46:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<B.size(); i++) { ^ user.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=B.size(); i<A.size(); i++) { ^ user.cpp: In function ‘std::vector<int> sum(std::vector<int>, int)’: user.cpp:66:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<A.size(); i++) { ^