Compilare: user.cpp: In function ‘int main()’: user.cpp:38:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.in","r",stdin); ^ user.cpp:39:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("qxy.out","w",stdout); ^ user.cpp:41:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); len=trunc(sqrt(n)); ^ user.cpp:43:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (int i=1;i<=n;i++) scanf("%d",&t[i]); ^ user.cpp:45:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:47:93: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (int i=1;i<=m;i++) scanf("%d %d %d %d",&v[i].x,&v[i].y,&v[i].xx,&v[i].yy),v[i].pos=i; ^