#include <fstream>
using namespace std;

#define IN "factorial.in"
#define OUT "factorial.out"

ifstream fin(IN);
ofstream fout(OUT);

long long numar=1,p=1,n;

void formare();
int rezolva();

int main()
{
    fin>>n;
    formare();
    rezolva();
    fout<<rezolva()<<'\n';
    return 0;
}

void formare()
{
int i;
for(i=1;i<=n;i++)
p=p*10;

}

int rezolva()
{
    int i=0;
    int ok=0;
while(ok==0)
      {
      i++;
      numar=numar*i;
      if(numar%p==0) {return i;ok=1;}
      }



}