sczyyds
sczyyds
sczyyds
I can't forget

你需要知道怎么求位数

#include<cmath>
#include<cstdio>
#include<iostream>
#define ll long long
using namespace std;
ll n;
int main(){
    //scanf("%lld",&n);
    cin>>n;
    ll l=0,r=2000000009;
    while(l<r){
         ll mid=(l+r)>>1;
         if((ll)(mid*log10(1.0*mid))+1<n)
         l=mid+1;
         else
         r=mid;
    } 
    cout<<l<<endl;
    return 0;
}