Compilare: user.cpp: In function ‘int main()’: user.cpp:31:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (t < Hash[dif % MOD].size() && Hash[dif % MOD][it] != dif) ++ it; ^ user.cpp:33:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (it == Hash[dif % MOD].size()) ++ nr_sol,Hash[dif % MOD].push_back(dif); ^ user.cpp:12:34: 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:13:36: 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:16:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.cpp:21:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:24:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val[i]); ^