#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long l, r, sum = 0;
	cin >> l >> r;
	for(int i = l;i <= r;i++)
	{
		int num = 0, ts = i;
		while(ts)
		{
			num = ts % 10;
			if(num == 2)
				sum++;
			ts /= 10;
		}
	}
	cout << sum;
	return 0;
}