#include<bits/stdc++.h>
using namespace  std;
int a,b,ans; 
int  main( ) 
{   
    cin>>a>>b;
    for (int i=a;i<=b;i++)
    {
        int ok=1,num[10]={0,0,0,0,0,0,0,0,0,0},it=i;
        while (it)
        {
            num[it%10]++;
            it/=10;
        }
        for (int j=0;j<=9;j++)
            if (num[j]%2!=0)
                ok=0;
        if (ok)
            ans++;
    }
    cout<<ans;
    return 0;   
}