#include<algorithm>
#include <cmath>
using namespace std;
int weishu(int n)
{
	int i;
	for ( i = 1;; i++)
	{
		if (n / pow(10, i) == 0) return i;
	}
}
void fenjie(int n, int x[])
{
	for (int i = 0; i < weishu(n); i++)
	{
		x[i] = n / int (pow(10, i)) % 10;
	}
}
int tongji(int x[], int n)//统计数组中的2
{
	int count = 0;
	for (int i = 0; i < n; i++)
	{
		if (x[i] == 2) count++;
	}
	return count;
}
int main() {
	int L, R; cin >> L >> R;
	int res = 0;
	for (int i = L; i <= R; i++)
	{
		int* p = new int[weishu(i)];
		fenjie(i, p);
		res += tongji(p, weishu(i));
		delete p;
	}
	cout << res;
}```