Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:129:31: 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:103:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omizi.in", "r", stdin); ^ user.cpp:104:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:107:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ user.cpp:117:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ user.cpp: In function ‘void solve()’: user.cpp:144:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %c", &a, &b); ^ user.cpp: In function ‘void write()’: user.cpp:204:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("omizi.out", "w", stdout); ^ user.cpp: In function ‘void solve()’: user.cpp:57:52: warning: ‘qpos’ may be used uninitialized in this function [-Wmaybe-uninitialized] update(rson, mid + 1, r, p, val1, val2); ^ user.cpp:137:18: note: ‘qpos’ was declared here int i, a, p, qpos, val; ^