NOD ( Number of divisor)

  ll n;cin>>n;
  map<ll,ll>mp;

  for(ll i=2; i<=n; i++){
    ll tmp = i;

    for(ll j=2; j*j<=tmp; j++){
      if(tmp%j == 0){
        while(tmp%j == 0){
          mp[j]++;
          tmp/=j;
        }
      }
    }
    if(tmp>1)mp[tmp]++;
  }