Compilare: user.cpp: In function ‘std::ostream& operator<<(std::ostream&, std::vector<std::vector<con> >&)’: user.cpp:35:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < g.size(); i++) ^ user.cpp:37:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0; j < g[i].size(); j++) o << i + 1 << " --" << g[i][j].cost << "--> " << g[i][j].dest + 1 << '\n'; ^ user.cpp: In function ‘std::ostream& operator<<(std::ostream&, const std::vector<int>&)’: user.cpp:44:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < v.size(); i++) o << v[i] << ' '; ^ user.cpp: In function ‘int main()’: user.cpp:67:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < graph[e].size(); i++) ^ user.cpp:83:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < distTo.size(); i++) ^