#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int m;
int nrZerouri(int n)
{
    int s=0,p=5;
    while(p<=n)
    {
        s+=n/p;
        p*=5;
    }
    return s;
}
int main()
{
    int n=5;
    in>>m;
    if(m==0)
        out<<"1";
    else
    {
        while(nrZerouri(n)!=m && nrZerouri(n)<m)
            n+=5;
        if(nrZerouri(n)==m)
            out<<n;
        else
            out<<"-1";
    }
    return 0;
}