Compilare: user.cpp: In function ‘int main()’: user.cpp:63:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < euler_cycle.size() && !list[euler_cycle[i]].size(); i++); ^ user.cpp:64:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i < euler_cycle.size()) ^ user.cpp:69:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < euler_cycle.size() - 1; i++) ^