Compilare: user.cpp:10:30: warning: integer constant is so large that it is unsigned [enabled by default] const unsigned long long a = 10000000000000000000; ^ user.cpp: In function ‘int main()’: user.cpp:26:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (c < a){ ^ user.cpp:28:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (c >= a){ of << "-1\n"; break; } ^