Compilare: user.c: In function 'read': user.c:16: warning: unused variable 'j' user.c: In function 'precompute': user.c:31: warning: implicit declaration of function 'sqrt' user.c:31: warning: incompatible implicit declaration of built-in function 'sqrt' user.c: In function 'bf': user.c:56: warning: left-hand operand of comma expression has no effect user.c:56: warning: value computed is not used user.c:56: warning: value computed is not used