Compilare: user.cpp: In function ‘int main()’: user.cpp:14:6: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (x == 0) if (v[upper_bound(v + 1, v + n + 1, a) - v - 1] == a) fout << upper_bound(v + 1, v + n + 1, a) - v - 1; ^ user.cpp:20:17: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("pause"); ^