Compilare: user.cpp: In function ‘int main()’: user.cpp:36:32: warning: format ‘%ld’ expects argument of type ‘long int’, but argument 2 has type ‘std::set<std::pair<long int, long int> >::size_type {aka unsigned int}’ [-Wformat=] printf("%ld\n",S.size()); ^ user.cpp:15:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sea2.in","r",stdin); ^ user.cpp:16:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sea2.out","w",stdout); ^ user.cpp:18:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld",&n); ^ user.cpp:20:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld",&x,&y); ^