Compilare: user.cpp: In function ‘void DFS(int, int)’: user.cpp:25:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < Gr[X].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:45:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < Euler.size(); i++) { ^ user.cpp:51:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < Euler.size(); i++) { ^ user.cpp:55:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; (1 << j) < Euler.size(); j++) { ^ user.cpp:56:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i + (1 << j) - 1 < Euler.size(); i++) { ^ user.cpp:34:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.in","r",stdin); ^ user.cpp:35:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("lca.out","w",stdout); ^ user.cpp:37:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &N, &M); ^ user.cpp:39:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &X); ^ user.cpp:68:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &X, &Y); ^