#include <iostream>
#include <cstdio>
#include <iomanip>
#include <fstream>
using namespace std;
int main(){
freopen("p1031.in","r",stdin);
freopen("p1031.out","w",stdout);
int n,i=-1,k=0,s=0;
cin>>n ;
while(s<n){
i+=2;
k+=2;
s=s+i;
};
cout<<k ;
fclose(stdin);
fclose(stdout);
return 0;
}
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