#include <fstream>

using namespace std;

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

long long p, rez, pas, r;

long long zero(int n)
{
    int nr = 0;
    while(n != 0)
    {
        nr += n/5;
        n /= 5;
    }
    return nr;
}

long long solve(int p)
{
    pas = 10000000;
    while(pas != 0)
    {
        if(zero(r + pas) < p)
            r += pas;
        pas /= 2;
    }
    if(zero(r + 1) == p) out<<r+1;
    else out<<'-1';
}

int main()
{
    in>>p;
    solve(p);
    return 0;
}