Compilare: user.cpp: In function ‘void answer()’: user.cpp:13:8: warning: unused variable ‘ans’ [-Wunused-variable] int ans = 0; ^ user.cpp: In function ‘int main()’: user.cpp:36:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix.in", "r", stdin); ^ user.cpp:37:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix.out", "w", stdout); ^ user.cpp:39:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &t); ^ user.cpp:42:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%s\n", s + 1); ^