Compilare: user.cpp: In function ‘int main()’: user.cpp:63:29: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] for (int i = 1; (i << i - 1) < n; i++) { ^ user.cpp:66:28: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] int length = (1 << i - 1); ^ user.cpp:38:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ghicit.in", "r", stdin); ^ user.cpp:39:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ghicit.out", "w", stdout); ^ user.cpp:41:16: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s + 1); ^ user.cpp:62:9: warning: ‘now’ may be used uninitialized in this function [-Wmaybe-uninitialized] int now, last; ^ /tmp/cc7QuRtN.o: In function `main': user.cpp:(.text.startup+0x56): warning: the `gets' function is dangerous and should not be used.