Compilare: user.cpp: In function ‘int main()’: user.cpp:49:48: warning: format ‘%lf’ expects argument of type ‘double*’, but argument 2 has type ‘long double*’ [-Wformat=] scanf("%lf%lf",&v[i].first,&v[i].second); ^ user.cpp:49:48: warning: format ‘%lf’ expects argument of type ‘double*’, but argument 3 has type ‘long double*’ [-Wformat=] user.cpp:63:31: warning: format ‘%lf’ expects argument of type ‘double’, but argument 2 has type ‘long double’ [-Wformat=] printf("%.9lf\n",sol/(2.0)); ^ user.cpp:41:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.in","r",stdin); ^ user.cpp:42:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.out","w",stdout); ^ user.cpp:43:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:44:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&k); ^ user.cpp:49:49: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf",&v[i].first,&v[i].second); ^