Compilare: user.cpp: In function ‘int main()’: user.cpp:17:9: warning: unused variable ‘x’ [-Wunused-variable] int x,y; ^ user.cpp:13:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("log.in","r",stdin); ^ user.cpp:15:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld%ld%ld%ld",&n,&t1,&t2,&t3); ^ user.cpp:20:36: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld%ld",&a[i],&b[i]); ^