Compilare: user.cpp: In function ‘void read()’: user.cpp:43:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < back[x].size(); j++) ^ user.cpp:46:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < ini_list[y].size(); j++) ^ user.cpp: In function ‘void add_false_vertex()’: user.cpp:55:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (list[i].size() != in_gr[i]){ ^ user.cpp:59:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (list[i].size() > in_gr[i]) list[0].push_back(i), in_gr[i]++; ^ user.cpp: In function ‘int main()’: user.cpp:93:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tester.in", "r", stdin); ^ user.cpp:94:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tester.out", "w", stdout); ^