Compilare: user.cpp: In function ‘int main()’: user.cpp:55:26: warning: unused variable ‘w’ [-Wunused-variable] int n,i,j,k,cate,sol,w,xx,yy; ^ user.cpp:55:28: warning: unused variable ‘xx’ [-Wunused-variable] int n,i,j,k,cate,sol,w,xx,yy; ^ user.cpp:55:31: warning: unused variable ‘yy’ [-Wunused-variable] int n,i,j,k,cate,sol,w,xx,yy; ^ user.cpp:53:39: 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:54:41: 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:57:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n); ^ user.cpp:60:41: 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); ^