Compilare: user.cpp: In function ‘int main()’: user.cpp:24:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("checkin.in","r",stdin); ^ user.cpp:25:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("checkin.out","w",stdout); ^ user.cpp:29:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:30:55: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i = 1; i <= N; ++i) scanf("%d %d",&A[i],&B[i]); ^ user.cpp:32:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&K,&P); ^ user.cpp:27:21: warning: ‘res’ may be used uninitialized in this function [-Wmaybe-uninitialized] int i,st,dr,mid,res,ticket=oo; ^