Compilare: user.cpp: In function ‘void pop_hash(unsigned int)’: user.cpp:20:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < H[x % mod].size(); ++ i) ^ user.cpp:21:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (H[x % mod][i] == x) ^ user.cpp: In function ‘int in_hash(unsigned int)’: user.cpp:30:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < H[x % mod].size(); ++ i) ^ user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (H[x % mod][i] == x) ^ user.cpp: In function ‘void dfs(int)’: user.cpp:55:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < V[x].size(); ++ i) ^ user.cpp: In function ‘void read()’: user.cpp:38:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbore3.in", "r", stdin); ^ user.cpp:39:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &S); ^ user.cpp:42:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^ user.cpp: In function ‘void write()’: user.cpp:68:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arbore3.out", "w", stdout); ^