Compilare: user.cpp: In function ‘std::vector<std::vector<int> > lee(std::vector<std::pair<int, int> >, const std::vector<std::vector<char> >&)’: user.cpp:52:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < matrix.size(); i++) ^ user.cpp:54:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < matrix[0].size(); j++) ^ user.cpp: In function ‘void print(const std::vector<std::vector<int> >&)’: user.cpp:67:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < m.size(); ++i) ^ user.cpp:69:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < m[0].size(); ++j) ^