#include <iostream>
using namespace std;

int n;

int nr_fin_zero(int n)
{
    int p = 0;
    while(n >= 5)
    {
        p += n / 5;
        n /= 5;
    }
    return p;
}

int caut_bin(int val)
{
    int st = 0, dr = 1e8, rez = -1;
    while(st <= dr)
    {
        int m = (st + dr) / 2;
        int x = nr_fin_zero(m);
        if(x < val)
        {
            st = m + 1;
        }
        else
        {
            if(x == val)
                rez = m;
            dr = m - 1;
        }
    }
    return rez;
}

int main()
{
    cin >> n;
    cout << caut_bin(n);
    return 0;
}