#include <iostream>
#include <fstream>
using namespace std;
long p,n,i=0,j,a[6],s=1,ok=0;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
   if(p!=0)
   while((a[5]!=p)&&(ok==0))
    {i+=5;j=i;
        while(j%5==0){a[5]++;j/=5;}
        if(a[5]>p)ok=1;
    }
    else i=1;
    if(ok==1)i=-1;
    cout<<i;
    return 0;
}