题目描述
<p>John and Brus believe that the digits 4 and 7 are lucky and all others are not. According to them, an almost lucky number is a number that contains at most one non-lucky digit in its decimal representation. Return the total number of almost lucky numbers between <b>a</b> and <b>b</b>, inclusive.</p>
输入格式
<p>Each line contains two integers a,b<=10^16</p>
输出格式
<p>For each line of input,output the total number of almost lucky numbers between <b>a</b> and <b>b</b>, inclusive.</p>
样例
样例输入 1
4 7
8 19
样例输出 1
4
4
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