Compilare: user.c: In function ‘prim’: user.c:7:16: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] for(i=2;i<=sqrt(a);i++) ^ user.c:7:16: warning: incompatible implicit declaration of built-in function ‘sqrt’ user.c:7:16: note: include ‘<math.h>’ or provide a declaration of ‘sqrt’ user.c: In function ‘main’: user.c:19:28: warning: implicit declaration of function ‘log’ [-Wimplicit-function-declaration] for(i=2;i<=n;i++,nr+=n/log(n)+1){ ^ user.c:19:28: warning: incompatible implicit declaration of built-in function ‘log’ user.c:19:28: note: include ‘<math.h>’ or provide a declaration of ‘log’ user.c:14:20: warning: unused variable ‘l’ [-Wunused-variable] int i,j,n,nr=0,l; ^ user.c:14:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,n,nr=0,l; ^ user.c:17:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^