#pragma GCC optimize("O3")
#include<bits/stdc++.h>
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define in insert
#define er erase
#define fr first
#define sc second
const int inf=INT_MAX;
const int nmax=1e7;
const int mod=1e9+7;
typedef long long ll;
using namespace std;
ll p;
int i,tmp,nrd,nrc;
int main()
{
	ios_base::sync_with_stdio(false);cin.tie(0);cerr.tie(0);cout.tie(0);
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	cin>>p;
	for(i=1;i<=nmax;i++)
	{
		tmp=i;
		while(!(tmp&1))tmp/=2,nrd++;
		while(!(tmp%5))tmp/=5,nrc++;
		if(min(nrd,nrc)>=p)
		{
			cout<<i<<endl;
			break;
		}
	}
	if(i==nmax+1)cout<<-1<<endl;
	return 0;
}