Compilare: user.cpp: In function ‘int main()’: user.cpp:30:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < graph[X].size(); ++i) ^ user.cpp:41:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < graph[a].size() && b; ++i) ^ user.cpp:48:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (b = 0; b < graph[a].size(); ++b) { ^ user.cpp:60:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < sol.size(); ++i) ^