Compilare: user.cpp: In function ‘int main()’: user.cpp:57:17: warning: unused variable ‘a’ [-Wunused-variable] int a = q . front (); ^ user.cpp:41:21: warning: unused variable ‘nr’ [-Wunused-variable] int n , i , k , nr , c2 , c3 = - (1 << 30); ^~ user.cpp: In function ‘int getbuff()’: user.cpp:21:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread (buff , 1 , BUFF , stdin); ^ user.cpp:31:44: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread (buff , 1 , BUFF , stdin); ^ user.cpp: In function ‘int main()’: user.cpp:38:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen (in , "r" , stdin); ^ user.cpp:39:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen (out , "w" , stdout); ^ user.cpp:40:36: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread (buff , 1 , BUFF , stdin); ^ user.cpp:65:29: warning: ‘c2’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf ("%d %d %d" , c2 - k + 1 , c2 , c3); ~~~^~~