#include<fstream>
using namespace std;

//definitie variabile
int frec[5000], n, i, x, radi, ok, p, k,s;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main(){
    fin>>p;

if(p==0)

fout<<1;

else

{

for(i=5;i<=5*p;i=i+5)

{

x=5;

while(x<=i)

{

k=i/x;

s=s+k;

x=x*5;

}

if(s==p)
{
ok=1;fout<<i;
break;
}
s=0;
}
}
if(ok==0)
fout<<-1;
return 0;
}