#include <fstream>

using namespace std;

ifstream cin ("fact.in");
ofstream cout ("fact.out");

int p, count_0, n;

void read()
{
    cin >> p;
}

int pow_5(int x)
{
    int cnt = 0;
    while(x % 5 == 0)
    {
        x /= 5;
        ++cnt;
    }
    return cnt;
}

void solve()
{
    int i;
    for(i = 5; count_0 < p; i += 5)
    {
        count_0 += pow_5(i);
    }
    n = i-5;
}

void print()
{
    if(p == 0)
    {
        cout << "1";
    }
    else
    {
        if(count_0 == p)
        {
            cout << n;
        }
        else
        {
            cout << "-1";
        }
    }
}

int main()
{
    read();
    solve();
    print();
    return 0;
}