#include<fstream.h>   
long int n,p,aux,x=0,i=0;   
int main ()   
{   
ifstream f("fact.in");   
ofstream g("fact.out");   
f>>p;   
if (p==0) g<<1;   
 else {   
while (x<p)   
    {i=i+5;aux=i;   
     while (aux)   
       {if (aux%5==0) {x++;aux=aux/5;}   
        else break;}   
    }   
if (x==p) g<<i;   
    else g<<-1;   
       }   
f.close();   
g.close();   
return 0;   
}