#include<stdio.h>
int five[1000000];
int main()
{
	long long i,nr=0,aux;
	int p;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);
	if(p)
	{
	for(i=1;;++i)
	{
		aux=i/5;
		if(aux%5)
			five[i]+=1;
		if(!(aux%5)||(aux&&!(i%5)))
			five[i]=five[aux]+1;
		nr+=five[i];
		if(nr==p||nr>p)
			break;
	}
	if(nr>p)
		printf("-1");
	else
		printf("%lld",i*5);
	}
	else
		printf("1");
	return 0;
}