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

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var r = (int)Math.Sqrt(n);
        var ans = n;
        for (var i = Math.Max(2, r / 2); i < r * 2 && i <= n; ++i)
        {
            var a = n / i;
            var k = (n - 1) / (i - 1);
            if ((n - i) % k == 0)
            {
                ans = Math.Min(ans, a + i - 1);
            }
            else
            {
                ans = Math.Min(ans, Math.Max(a + i - 2, a + n - a * i));
            }
        }
        WriteLine(ans);
    }
}