Compilare: user.cpp: In function ‘int main()’: user.cpp:75:17: warning: unused variable ‘a’ [-Wunused-variable] int a = q . front (); ^ user.cpp:46:21: warning: unused variable ‘nr’ [-Wunused-variable] int n , i , k , nr , c2 , c3 = -30100; ^~ user.cpp: In function ‘int getbuff()’: user.cpp:25:44: 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:35:44: 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:44:31: 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:45:36: 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:83:40: warning: ‘c2’ may be used uninitialized in this function [-Wmaybe-uninitialized] cout << c2 - k + 1 << ' ' << c2 << ' ' << c3; ^~~