Compilare: user.cpp: In function ‘int main()’: user.cpp:10:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1 ; i<=n ; i++) ^ user.cpp:15:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2 ; i<n ; i++) ^ user.cpp:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2 ; i<=n ; i++) ^