Compilare: user.cpp: In function ‘int main()’: user.cpp:57:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("cerere.in","r",stdin); ^ user.cpp:58:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("cerere.out","w",stdout); ^ user.cpp:59:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ user.cpp:61:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &str[i]); ^ user.cpp:64:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x,&y); ^ user.cpp:39:28: warning: iteration 28u invokes undefined behavior [-Waggressive-loop-optimizations] Log2[i]=Log2[i/2]+1; ^ user.cpp:38:5: note: containing loop for(i=2;i<Nmax;++i) ^ user.cpp:72:15: warning: ‘rad’ may be used uninitialized in this function [-Wmaybe-uninitialized] Dfs(rad,0); ^