Compilare: user.cpp: In function ‘int main()’: user.cpp:39:50: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (it < Hash[dif % MOD].size() && Hash[dif % MOD][it] != dif) ++ it; ^ user.cpp:41:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (it == Hash[dif % MOD].size())++ nr_sol; ^ user.cpp:13:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("progr.in","r",stdin); ^ user.cpp:14:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("progr.out","w",stdout); ^ user.cpp:17:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:22:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:25:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val[i]); ^