Compilare: user.cpp: In function ‘int main()’: user.cpp:31:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("shop.in","r",stdin); ^ user.cpp:32:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("shop.out","w",stdout); ^ user.cpp:33:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %lld",&N,&C,&L); ^ user.cpp:34:63: 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 %d",&a[i],&b[i]),ind[i]=i; ^