Compilare: user.cpp: In function ‘std::vector<int> uni(std::vector<std::pair<int, int> >)’: user.cpp:22:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); ++i){ ^ user.cpp: In function ‘void dfs(int)’: user.cpp:34:53: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0, Fiu = v[Nod][0]; i < v[Nod].size(); ++i, Fiu = v[Nod][i]) ^ user.cpp: In function ‘int main()’: user.cpp:68:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < Ans.size(); ++i){ ^ user.cpp:69:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < Ans[i].size(); ++j) ^ user.cpp:57:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.in", "r", stdin); ^ user.cpp:58:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("biconex.out", "w", stdout); ^ user.cpp:59:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:62:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &A, &B); ^