#include<fstream.h>
ifstream f("fact.in");
ofstream g("fact.out");
long a[13]={5,25,125,625,3125,15625,78125,390625,1953125,9765625,48828125,244140625};
int main()
{long p,q=0,n;
f>>p;
n=p*4;
while(n%5)
{n--;}
if(p==0)g<<-1;
else{
for(int i=0;i<=11;i++)
q+=n/a[i];

while(q<p)
{n+=5;
for(i=0;i<=11;i++)
if(n%a[i]==0)q++;
}
if(q==p)g<<n;
else g<<-1;}
return 0;
g.close();
f.close();
}