Compilare: user.cpp: In function ‘void Preprocessing()’: user.cpp:45:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i <= 2 * E.size() + 1; i++) ^ user.cpp:52:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < E.size(); i++) ^ user.cpp:55:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < E.size(); i++) ^ user.cpp: In function ‘void Euler(int, int)’: user.cpp:66:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[node].size(); i++) { ^ user.cpp: In function ‘void Solve()’: user.cpp:28:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^ user.cpp: In function ‘void Read()’: user.cpp:73:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in", "rt", stdin); ^ user.cpp:74:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out", "wt", stdout); ^ user.cpp:75:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &Q); ^ user.cpp:79:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &f); ^