The Almost Lucky Numbers

<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>

<p> Each line contains two integers a,b&lt;=1,000,000 </p>

<p> For each line of input,output the total number of almost lucky numbers between <b>a</b> and <b>b</b>, inclusive. </p>