Compilare: user.cpp: In function ‘int main()’: user.cpp:4:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pitagora2.in", "r", stdin); ^ user.cpp:5:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pitagora2.out", "w", stdout); ^ user.cpp:6:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int n; scanf ("%d",&n); printf ("-1"); return 0;} ^