Compilare: user.cpp: In function ‘void read()’: user.cpp:28:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:31:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d ",&x,&y,&z); ^ user.cpp: In function ‘void solve()’: user.cpp:191:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&x,&y,&z); ^ user.cpp: In function ‘int main()’: user.cpp:218:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb4.in","r",stdin); ^ user.cpp:219:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("arb4.out","w",stdout); ^ user.cpp: In function ‘void dfs(int, int, int)’: user.cpp:57:17: warning: ‘node’ may be used uninitialized in this function [-Wmaybe-uninitialized] p[path[node]].pb(k),path[k]=path[node]; ^ user.cpp: In function ‘void solve()’: user.cpp:193:30: warning: ‘lca’ may be used uninitialized in this function [-Wmaybe-uninitialized] chain_update(lca,x,z); ^