#include <stdio.h>

int main() {
   int x,y,mark1=0;
   scanf("%d%d",&x,&y);
   for(int i=x;i<=y;i++)
   {
    int mark=i,sum=0;
      while(mark)
      {
        sum+=mark%10;
        mark/=10;
      }
      if(sum%5==0)
      mark1++;
   }
   printf("%d",mark1);
    return 0;
}