Compilare: user.cpp: In function ‘int main()’: user.cpp:13:11: warning: unused variable ‘x’ [-Wunused-variable] int n,x,y,i,perpen,trapez=0,k,j,secv; ^ user.cpp:13:13: warning: unused variable ‘y’ [-Wunused-variable] int n,x,y,i,perpen,trapez=0,k,j,secv; ^ user.cpp:13:17: warning: variable ‘perpen’ set but not used [-Wunused-but-set-variable] int n,x,y,i,perpen,trapez=0,k,j,secv; ^ user.cpp:11:35: 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:12:37: 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:14:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:16:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&v[i].xx,&v[i].yy); ^