#include <fstream>
using namespace std;
int y,p,i,x,a;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
    i=0;
    while(y<p)
     {
        i=i+5;
        x=i;
        y++;
        while((x/5)%5==0)
        {
         x=x/5;
         y++;
        }
     }
    if(p==0) fout<<1;
    if(y==p)
        fout<<i;
    else fout<<-1;
    return 0;
}