下面是我的代码：

#include<iostream>
using namespace std;
unsigned long long ans=0,ZDY,ZKY;
bool check(unsigned long long x)
{
	while(x)
	{
		if(x%10==4||x%10==9)
			return true;
		x/=10;
	}
	return false;
}
int main()
{
	cin>>ZDY>>ZKY;
	for(unsigned long long i=ZDY;i<=ZKY;i++)
	{
		if(check(i))
			ans++;
	}
	cout<<ans<<'\n';
	return 0;
}