#define REP(a,b) for(int a=0; a<(b); ++a)
#define FWD(a,b,c) for(int a=(b); a<(c); ++a)
#define FWDS(a,b,c,d) for(int a=(b); a<(c); a+=d)
#define BCK(a,b,c) for(int a=(b); a>(c); --a)
#define ALL(a) (a).begin(), (a).end()
#define SIZE(a) ((int)(a).size())
#define VAR(x) #x ": " << x << " "
#define FILL(x,y) memset(x,y,sizeof(x))
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))
#define x first
#define y second
#define st first
#define nd second
#define pb push_back
#define nleft (n<<1)
#define nright (nleft+1)

#include<vector>

using namespace std;
#include<fstream>
ifstream fin("fact.in");
ofstream fout("fact.out");

#define NMAX 1000000

const int INF = 0x3f3f3f3f;
const int dx[] = {0,0,-1,1}; //1,1,-1,1};
const int dy[] = {-1,1,0,0}; //1,-1,1,-1};

typedef long long LL;
typedef pair<int, int> PII;
typedef long double K;
typedef pair<K, K> PKK;
typedef vector<int> VI;

int n,m,i,j;

inline int zeros(int a)
{
	int n=0;
	while(a)
	{
		n+=a/5;
		a/=5;
	}
	return n;
}

int lower_binary(int val)
{
    int i, step;
    for(step=1;step<=INF;step<<=1);

    for(i=INF; step; step>>=1)
        if(i-step>0 && zeros(i-step)>=val)
				i-=step;
    return i;
}


int main()
{
	fin>>n;
	i=lower_binary(n);
	if(zeros(i)==n)
		fout<<lower_binary(n);
	else
		fout<<-1;
	return 0;
}