Compilare: user.cpp: In function ‘int main()’: user.cpp:23:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ograzi.in","r",stdin); ^ user.cpp:24:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ograzi.out","w",stdout); ^ user.cpp:25:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&n,&m,&w,&h); ^ user.cpp:28:61: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] Hash[((x/w)*1000+y/h)%MOD].push_back(make_pair(x,y)); ^ user.cpp:31:39: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] sol+=hash_find(make_pair(x,y)); ^