Compilare: user.cpp: In function ‘void task_b()’: user.cpp:43:21: warning: unused variable ‘l’ [-Wunused-variable] int ant, len, top, l, r; ^ user.cpp:43:24: warning: unused variable ‘r’ [-Wunused-variable] int ant, len, top, l, r; ^ user.cpp: In function ‘int main()’: user.cpp:95:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("charlie.in", "r", stdin); ^ user.cpp:96:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("charlie.out", "w", stdout); ^ user.cpp:98:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %s", &tsk, str); ^ user.cpp:88:36: warning: ‘top’ may be used uninitialized in this function [-Wmaybe-uninitialized] for (int i = top; i != n; i = dr[i]) ^ user.cpp:43:16: note: ‘top’ was declared here int ant, len, top, l, r; ^