include<bits/stdc++.h>

using namespace std; int main(){ double c;

 cin>>c;   
 double sum= 0.0; 
 int n=1;   
 while (true){  
     sum+=1.0/(n+1);  
     if (sum>=c)break; 
     n++;    
 }
 cout<<n<<endl; 
 return 0;

}