#include <bits/stdc++.h>
#define for0(i, n) for(int i = 0; i < n; i++)
#define for1(i, n) for(int i = 1; i <= n; i++)
#define pb push_back
#define mp make_pair
#define all(v) v.begin(), v.end()
#define V vector<int>
#define VP vector<pair<int, int> >
#define FASTIO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
using namespace std;
#ifdef _WIN32
#include <windows.h>
#define print(x) PRINT(x, #x)
template<typename T> inline const void PRINT(T VARIABLE, string NAME)
{
#ifndef ONLINE_JUDGE /// ONLINE_JUDGE IS DEFINED ON CODEFORCES
    HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
    SetConsoleTextAttribute(hConsole, 10);
    cerr << NAME << " = " << VARIABLE;
    SetConsoleTextAttribute(hConsole, 7);
    cerr << '\n';
#endif
}
#else
#define print(x) 0
#endif
typedef long long ll;
typedef unsigned long long ull;
const ll INFLL = 2 * (ll)1e18 + 100;
const int INFINT = 2 * (int)1e9 + 100;
const double PI = atan(1) * 4;
const double EPS = 1e-12;
const int SEED = 1e3 + 7;

const int MOD = 1e9 + 7; /// careful here (7 or 9, 66.. etc)
const int NMAX = 1e6 + 5;


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

int cnt_zero(int x)
{
    int cinci = 5, cur = 1;
    while(cinci <= x) cinci *= 5, cur++;
    cinci /= 5;
    cur--;

    int ret = 0, nr_cinci = 0;
    while(cinci > 1)
    {
        int temp = x / cinci - nr_cinci;
        nr_cinci += x / cinci - nr_cinci;
        ret += temp * cur;
        cinci /= 5;
        cur--;
    }

    return ret;
}

int main()
{
    int p;
    cin >> p;
    if(p == 0) return cout << 1, 0;
    int l = 0, r = 5 * (int)1e8;
    for1(_, 50)
    {
        int m = (l + r) / 2;
        int zero = cnt_zero(m);
        if(zero == p && m % 5 == 0) return cout << m, 0;
        if(zero >= p) r = m;
        else l = m;
    }
    cout << -1;

    return 0;
}