using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static long NN => long.Parse(ReadLine());
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var sq = (long)Math.Sqrt(n);
        while ((sq + 1) * (sq + 1) <= n) ++sq;
        WriteLine(sq);
    }
}