#pragma region Header
#define _CRT_SECURE_NO_WARNINGS
#include <array>
#include <bits/stdc++.h>
#include <unordered_set>
#include <unordered_map>
#include <chrono>
#include <map>
#include <thread>
#include <mutex>
#include <future>

typedef unsigned long long ull;
typedef long long ll;
typedef unsigned int uint;
#define endl '\n'
using namespace std;
#if 1

#include <fstream>

ifstream fin("fact.in");
ofstream fout("fact.out");
#define cin fin
#define cout fout
#endif

#pragma endregion

ll GetNrZero(ll n)
{
	ll s = 0;
	while (n)
	{
		n /= 5;
		s += n;
	}
	return s;
}

ll Cb(ll p)
{
	ll st = 1, dr = 1e8 * 5;
	ll ans = -1;
	while (st <= dr)
	{
		ll md = (st + dr) / 2;
		ll nrzr = GetNrZero(md);
		if (nrzr == p)
		{
			dr = md - 1;
			ans = md;
		}
		else if (nrzr > md)
			dr = md - 1;
		else
			st = md + 1;
	}
	return ans;
}

int main()
{
	int p;
	cin >> p;
	cout << Cb(p);

}