Compilare: user.cpp: In function ‘int main()’: user.cpp:10:20: warning: unused variable ‘lmax’ [-Wunused-variable] int n,i,j,x1,y1,l,lmax,p,k=0; ^ user.cpp:10:25: warning: unused variable ‘p’ [-Wunused-variable] int n,i,j,x1,y1,l,lmax,p,k=0; ^ user.cpp:11:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in","r",stdin); ^ 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("trapez.out","w",stdout); ^ user.cpp:13:16: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:15:32: 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); ^