Compilare: user.cpp: In function ‘int main()’: user.cpp:19:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dunarea.in","r",stdin); ^ user.cpp:20:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dunarea.out","w",stdout); ^ user.cpp:22:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&a,&b,&n); ^ user.cpp:24:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&v[i].st,&v[i].dr); ^ user.cpp:32:17: warning: ‘ai’ may be used uninitialized in this function [-Wmaybe-uninitialized] if(v[ai].dr >= b) ^