#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main()
{long p,s,i,ci;
fin>>p;
s=0;
for(i=5;s<p;i+=5)
    {ci=i;
    if (ci%25==0)
        while(ci%5==0)
            {ci=ci/5;
            s++;
            }
        else s++;
    }
if(p==0) fout<<i-4;
    else if (p>0) fout<<i-5;
            else fout<<-1;
    return 0;
}