Compilare: user.c: In function ‘prim’: user.c:8:16: warning: implicit declaration of function ‘sqrt’ [-Wimplicit-function-declaration] for(i=2;i<=sqrt(a);i++) ^ user.c:8:16: warning: incompatible implicit declaration of built-in function ‘sqrt’ user.c:8:16: note: include ‘<math.h>’ or provide a declaration of ‘sqrt’ user.c: In function ‘main’: user.c:38:30: warning: implicit declaration of function ‘pow’ [-Wimplicit-function-declaration] fi*=(p[i]-1)*pow(p[i],pw[i]-1); ^ user.c:38:30: warning: incompatible implicit declaration of built-in function ‘pow’ user.c:38:30: note: include ‘<math.h>’ or provide a declaration of ‘pow’ user.c:18:5: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^