#include<iostream>
using namespace std;
int main() {
	int ansx=0;
	int left,right;
	cin>>left>>right;
	while(left<=right) {
		int k=1;
		int g=left;
		while(g>0) {
			int g_=g/k%10;
			if(g_==2) {
				ansx++;
			}
			g/=k;
			k*=10;
		}
		left++;
	}
	cout<<ansx;
	return 0;
}

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