#include<bits/stdc++.h>
using namespace std;
int m;
int j(int y){
	int g=0;
	while(y){
		g=y%10;
		y/=10;
        if(g==2) m++;
	}
	return m;
}
int main(){
	int l,r,s=0;
	cin>>l>>r;
	for(int i=l;i<=r;i++){
		if(j(i)>0) s+=m;
        m=0;
	}
	cout<<s;
}

/**************************************************************
	Problem: 1662
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:37 ms
	Memory:2072 kb
****************************************************************/