Compilare: user.cpp: In function ‘int formula()’: user.cpp:72:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:129:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < r.size(); i++){ ^ user.cpp:89:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.in", "r", stdin); ^ user.cpp:90:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.out", "w", stdout); ^ user.cpp:93:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^