#include<cstdio>
using namespace std;
FILE *f=fopen("fact.in","r");
FILE *g=fopen("fact.out","w");
long p,i,ci;
int j,nr;
int main()
{
	fscanf(f,"%ld",&p);
	if(p==0) fprintf(g,"1");
	else
	{
	while(p>0)
	{
		i+=5;
		j=i;
		nr=0;
		ci=5;
		while(j%ci==0)
		{
			nr++;
			ci*=5;
		}
		p-=nr;
	}
	if(p<0) fprintf(g,"-1");
	else fprintf(g,"%ld",i);
	}
	return 0;
}