#include <stdio.h>
int cnum(int a,int b)
{
     int i=0;
     int set=0;
     int count=0;
     for(i=a;i<=b;i++)
     {
        int ptr=i;
         while(ptr)
         {
            set=ptr%10;
            ptr=ptr/10;
            if(set==2)
            count++;
         }
     }
     return count;
}
int main() {
    int a=0;
    int b=0;
    scanf("%d %d",&a,&b);
    int sut= cnum(a,b);
   printf("%d",sut);
    return 0;
}