暴力打表。

#include
     
      #include
      
       #include
       
        #include
        
         #include
         
          using namespace std;long long a[10000];long long L, R;int tot;void dfs(long long num, int len){    if (len > 16) return;    if (num>=1&&num<=1000000000000000&&num % 48 == 0) a[tot++] = num;    dfs(num * 10 + 4, len + 1);    dfs(num * 10 + 8, len + 1);}void init(){    tot = 0;    dfs(4, 1);    dfs(8, 1);}int main(){    init();    while (~scanf("%lld%lld", &L, &R))    {        long long ans = 0;        for (int i = 0; i < tot; i++)            if (a[i] >= L&&a[i] <= R) ans++;        printf("%lld\n", ans);    }    return 0;}