Compilare: user.cpp: In function ‘void solve()’: user.cpp:21:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() < L || (d.size() >= L && d.size() < U)) ^ user.cpp:21:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() < L || (d.size() >= L && d.size() < U)) ^ user.cpp:21:57: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() < L || (d.size() >= L && d.size() < U)) ^ user.cpp:26:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() >= L && d.size() <= U) ^ user.cpp:26:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() >= L && d.size() <= U) ^ user.cpp:29:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size() == U) ^ user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(d.size() > L) ^ user.cpp: In function ‘void read()’: user.cpp:11:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sum2.in", "r", stdin); ^ user.cpp:12:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sum2.out", "w", stdout); ^ user.cpp:13:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &N, &L, &U); ^ user.cpp:15:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i]); ^