Compilare: user.cpp: In function ‘int search_(int)’: user.cpp:22:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i + step < v.size() && v[i+step].F < x) ^ user.cpp: In function ‘int main()’: user.cpp:67:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (STEP = 1; STEP < v.size(); STEP <<= 1); ^ user.cpp:58:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("loto.in","r",stdin); ^ user.cpp:59:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("loto.out","w",stdout); ^ user.cpp:61:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &s); ^ user.cpp:64:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", a + i); ^