洛谷 P2759 奇怪的函数

https://www.luogu.org/problemnew/show/P2759

 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #include<vector>
 #include<cmath>
 using namespace std;
 #define fi first
 #define se second
 #define mp make_pair
 #define pb push_back
 typedef long long ll;
 typedef unsigned long long ull;
 typedef pair<int,int> pii;
 ll n,l,r;
 int main()
 {
     ll mid;
     scanf("%lld",&n);
     l=;r=;
     while(r-l>)
     {
         mid=l+(r-l)/;
         if(mid*log10(mid)>=n-)    r=mid;
         else    l=mid;
     }
     printf("%lld",r);
     return ;
 }