Compilare: user.cpp: In function ‘long long int make_diff(std::string, std::string)’: user.cpp:18:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<a.size(); ++i) ^ user.cpp:21:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<b.size(); ++i) ^ user.cpp: In function ‘long long int verif(char, char)’: user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<s.size(); ++i) ^ user.cpp:39:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i<s.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:66:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i<s.size(); ++i) ^ user.cpp:73:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int q = 0; q < v.size()-1; ++q) ^