Compilare: user.cpp: In function ‘int main()’: user.cpp:5:60: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int N,F[1000005];long long r=0;int main(){fscanf(f,"%d",&N);for(int i=1;i<=N;i++){F[i]=i;}for(int i=2;i<=N;i++){if(F[i]==i){for(int j=i;j<=N;j+=i)F[j]=(F[j]/i)*(i-1);}r+=F[i];}fprintf(g,"%lld",2*r+1);return 0;} ^