HUD 4473

比赛的时候看都没看到这道题，现在直接看题外加解题报告，感觉好简单啊

思维啊，思维啊，思维啊

#include<cstdio>
#include<cmath>
typedef long long ll;

ll power3(ll n)
{
	ll ret=pow(n,1.0/3);
	while(ret*ret*ret<n)
		ret ++;
	while(ret*ret*ret>n)
		ret --;
	return ret;
}

ll power2(ll n,ll i)
{
	ll ret=pow(n/i,1.0/2);
	while(ret*ret*i<n)
		ret ++;
	while(ret*ret*i>n)
		ret --;
	return ret;
}

int main()
{
	ll n,id=0;
	while(~scanf("%I64d",&n))
	{
		ll q3=power3(n);
		ll ans=q3;
		ll i,j,t;
		for(i=1;i<=q3;i++)
		{
			t=n/(i*i);
			ans += (t-i)*3;
			ll q2=power2(n,i);
			ans += (q2-i)*3;
			for(j=i+1;j<=q2;j++)
			{
				t=n/(i*j);
				ans += (t-j)*6;
			}
		}
		printf("Case %I64d: %I64d\n",++id,ans);
	}
	return 0;
}