n,m=map(int(input().split())) sum=0 for i in range(n,m+1): s=str(i) l=len(s) if s[l-1]=='4': sum+=1 continue for j in range(0,l-1): if (s[j]=='6'and s[j+1]=='2') or s[j]=='4': sum+=1 break print(m-n+1-sum)