Compilare: user.c: In function ‘main’: user.c:13:5: warning: implicit declaration of function ‘abs’ [-Wimplicit-function-declaration] s=abs((n%p*(n+1)%p*(2*n+1)%p)%p/6-n%p*(n+1)%p/2); ^ user.c:8:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp,"%d",&n); ^ user.c:10:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fp,"%d",&p); ^