#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ar array
#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
    *this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define imie(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

ifstream in("fact.in");
ofstream out("fact.out");

int number_of_zeros(int n) {
	
	int s = 0;
	int a = 5;
	// numarul de zerouri este egal cu numar factorilor divizibili cu 5
	while(a <= n) {
		s += n/a;
		a *= 5;
	}
	
	// s - numar zerouri
	
	return s;	
}

int main() {

	int p, left, right, ans;
    in >> p;
	left = 1; 
	right = 100000000;
	while(left <= right) {
		int mid = left + (right-left)/2;
		if(number_of_zeros(mid) >= p) {
			ans = mid;
			right = mid - 1;
		}
		else {
			left = mid + 1;
		}
		debug() << imie(left) imie(mid) imie(right);
	}
		if(number_of_zeros(ans) == p) {
			out << ans;
		}
		else {
			out << -1;
		}
	
	return 0;
}

//2 -> 10! pentru ca 10! are 2 zerouri la final