Compilare: user.cpp: In function ‘int main()’: user.cpp:13:23: warning: unused variable ‘x’ [-Wunused-variable] int n,i,j,a=0,b=0,k=0,x,q; ^ user.cpp:11:33: 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:15:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:17:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld%lld",&vv[i].x,&vv[i].y); ^