#include <fstream>
using namespace std;

int main(){
ifstream fin("fact.in");
ofstream fout("fact.out");
long long p,nr,i,f,m,p5[1000];
fin>>p;
if(p==0){
  fout<<1;
  fout.close();
  return 0;
}
p5[1]=5;
f=1;
i=p*5;
while(p5[f]<=p*5){
  p5[f+1]=p5[f]*5;
  f++;
  i-=p*5/p5[f];
  }
for(nr=0,i=5;nr<p;i+=5){
  f=1;
  while(i%p5[f]==0)
    f++;
  nr+=f-1;
  }
if(nr==p) fout<<i-5;
else fout<<-1;
fout.close();
}