#include<iostream>
using namespace std;
int main()
{
	int L, R;
	while (cin >> L >> R) {//EOF结束输入 
		int ans = 0;//计数 
		for (int num = L; num <= R; num++) {
			int tmp = num;
			while (tmp > 0) {
				if (tmp%10 == 2)
					ans++;
				tmp /= 10;
			} 
		}
		cout << ans << endl;
	}
	return 0;
}