Compilare: user.cpp: In function ‘void update(int)’: user.cpp:10:15: warning: suggest parentheses around arithmetic in operand of ‘^’ [-Wparentheses] x += x&(x-1)^x; ^ user.cpp: In function ‘int main()’: user.cpp:44:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("txt.in", "r", stdin); ^ user.cpp:45:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("txt.out", "w", stdout); ^ user.cpp:47:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:49:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^