Compilare: user.cpp: In function ‘int main()’: user.cpp:29:21: warning: unused variable ‘st’ [-Wunused-variable] int i, ans = 0, st, dr; ^ user.cpp:29:25: warning: unused variable ‘dr’ [-Wunused-variable] int i, ans = 0, st, dr; ^ user.cpp:31:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("costperm.in", "r", stdin); ^ user.cpp:32:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("costperm.out", "w", stdout); ^ user.cpp:34:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ user.cpp:36:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &a [i]); ^