#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
const long long M=1000000000;
ifstream f("fact.in");
ofstream g("fact.out");
long long p,i=0,nr5=0;
inline int n5(long long p)
{
    int pow = 1, s = 0;
    while ( pow * 5 <= p)
    {
        pow *= 5;
        s += p/pow;

    }
    return s;

}
long long vf(long long i)
{
    while(nr5<p)
{
    i+=5;
    if(n5(i)==p) break;
}
return n5(i)==p ? i : -1 ;
}
int main()
{

cin>>p;if(p==0) g<<1;
else
cout<<vf(i);
    return 0;
}