Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:38:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < A[t].size(); ++i) { ^ In file included from /usr/include/c++/4.8/cassert:43:0, from user.cpp:3: user.cpp:40:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(p < b.size()); ^ user.cpp:44:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < a[t].size(); ++i) ^ user.cpp: In function ‘void read()’: user.cpp:21:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ", &n, &m); ^ user.cpp:24:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ", &x); ^ user.cpp:31:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ", &node[i], &k[i]); ^ user.cpp: In function ‘int main()’: user.cpp:58:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stramosi.in", "r", stdin); ^ user.cpp:59:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("stramosi.out", "w", stdout); ^