import java.io.*;
import java.util.*;

class Main
{
    public static void main(String args[])throws Exception
    {
        BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder();
        long n=Long.parseLong(bu.readLine());
        long r=root(n),ans=Math.min(n,r+(n-r*r)+2);
        System.out.print(ans);
    }

    static long root(long n)
    {
        long l=1,r=(int)1e9,ans=l,mid;
        while(l<=r)
        {
            mid=(l+r)>>1;
            if(mid*mid<=n)
            {
                ans=mid;
                l=mid+1;
            }
            else r=mid-1;
        }
        return ans;
    }
}