#include <fstream.h>
ifstream fin  ("fact.in");
ofstream fout ("fact.out");
int main() {
	int p, nz, b, stanga=0, dreapta=1000000000, mijloc, gasit=0;
	fin >> p;
	if (p) {
		while (!gasit && stanga<=dreapta) {
			mijloc=(stanga+dreapta)/2;
			b=5, nz=0;
			while (b<=mijloc) {
				nz+=mijloc/b;
				b*=5;
			}
			if (nz==p) gasit=1;
			else 
				if (nz>p) dreapta=mijloc-1;
				else stanga=mijloc+1;
		}
		if (gasit) fout << mijloc-mijloc%5;
		else fout << "-1";
	}
	else fout << '1';
	fout.close();
	return 0;
}