#include<cstdio>
 
int main()
{
  int l,r,i,k,ans=0;
  scanf("%d%d",&l,&r);
  for(i=l;i<=r;i++)
    for(k=i;k>0;k/=10)
      if(k%10==2)ans++;
  printf("%d\n",ans);
  return 0;
}
/**************************************************************
	Problem: 1662
	User: admin
	Language: C++
	Result: Accepted
	Time:45 ms
	Memory:1144 kb
****************************************************************/