#include<bits/stdc++.h> 
using namespace std;
int a,b,c=0,d=0;
bool s;
int main(){
	cin>>a>>b;
	for(int i=a;i<=b;i++){
		while(i> 0){
			if(i%10 <= c-1) s=true;
			else break; 
			i/=10;
		}
		if(s==true) c+=1;
    } 
	cout<<c;
	return 0;
}