#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <iomanip>
#include <stack>
#include <queue>
#include <vector>
#include <map>
#define intmax 0x7fffffff
using namespace std;
int l,r,ans;
int check(int num);
int main(int argc,char **argv)
{
    ios::sync_with_stdio(0);
    cin>>l>>r;
    for (short i=l;i<=r;i++)
        ans+=check(i);
    cout<<ans;
    return 0;
}
int check(int num)
{
    short cnt=0;
    while (num)
    {
        if (num%10==2)
            ++cnt;
        num/=10;
    }
    return cnt;
}