#include <iostream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int zero(int n)
{   int nr=0;
    while(n>=5)
    {
            nr++;
            n=n/5;
    }
    return nr;
}
int main()
{   long long n,r=0,pas;
    in>>n;
    pas=1<<30;
    while(pas)
    {
        if(zero(r+pas)<n)
            r+=pas;
        pas/=2;
    }
    if(zero(r+1)==n)
        out<<r+1;
    else
        out<<-1;
    return 0;
}