#include <iostream>
using namespace::std;

int write(int nr)
{
	FILE *fout;
	fout = fopen("fact.out","w");
	fprintf(fout,"%d",nr);
	fclose(fout);
	return 0;
}

int main()
{
	FILE *fin;
	char str[80];
	int p=0, count, n, total=0, nr, i;
	//long long int n;

	fin = fopen("fact.in", "r");
	fscanf(fin,"%d", &p);
	fclose(fin);
	if(p==0) printf("1");

	for(i=1;i<=p;i++)
	{
		nr = 5*i;
		count=0;
		while(nr%5 == 0)
		{
			count++;
			nr /= 5;
		};
		total += count;

		if(total==p) {write(5*i); break;}
		if(total>p) {write(-1); break;}
	}
		 
}