Compilare: user.cpp: In function ‘int main()’: user.cpp:59:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mission.in","r",stdin); ^ user.cpp:60:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mission.out","w",stdout); ^ user.cpp:62:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:65:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&v[ i ].x , & v[ i ].y ); ^ user.cpp:83:19: warning: ‘st’ may be used uninitialized in this function [-Wmaybe-uninitialized] for ( i = (st + 1)%n ; i !=st ; i = ( i + 1 ) % n ){ ^