#include <stdio.h>
int census(int L,int R)
{
    int count = 0;
for(int i = L;i<=R;i++)
{
if(i%10==2)
count++;
if(i%100/10==2)
count++;
if(i%1000/100==2)
count++;
if(i%10000/1000==2)
count++;
}
return count;
}

int main() {
int L,R;
scanf("%d %d",&L,&R);
int k = census( L,R);
printf("%d",k);
    return 0;
}