1 #include<cstdio>
 2 #include<cmath>
 3 #define maxx 10000000000
 4 using namespace std;
 5 unsigned long long x,ans,l=1,r=maxx;
 6 unsigned long long n;
 7 unsigned long long f(unsigned long long x){
 8     return (x*(log10(x))+1);
 9 }
10 int main(){
11     scanf("%lld",&n);
12     while(l<r){
13         x=(l+r)/2;
14         if(f(x)<n) l=x+1;
15         else r=x;
16     }
17     printf("%lld",l);
18     return 0;
19 }