#include<stdio.h>

int main()
{
	FILE *f = fopen("fact.in", "r");
	FILE *g = fopen("fact.out", "w");
	
	int p;
	int i = 0, bla;
	
	fscanf(f, "%d", &p);
	
	for(i=5; p>0; i+=5)
	{
		bla = i;
		while(bla%5 == 0)
		{
			bla/=5;
			p--;
		}
	}
	
	if(p == 0)
		fprintf(g, "%d", i-5);
	else
		fprintf(g, "-1");
	
	return 0;
}