//#include<stdio.h>
#include<fstream>
using namespace std;
FILE *in,*out;
int nr0,p;
int num,aux,aux2;
int main()
{
	//in=fopen("fact.in","rt");
	//out=fopen("fact.out","wt");
	ifstream in("fact.in");
	ofstream out("fact.out");
	//fscanf(in,"%d",&p);
	in>>p;

	if(p>0)
	{
		while(nr0<p)
		{
			num+=25;
			nr0+=4;
			aux=num;
			if(nr0<p)
			{
				while( !(aux%5) )
				{
					nr0++;
					aux/=5;
				}
			}
			else
			{
				aux2=nr0-p+1;
				num-=5*aux2;
				nr0-=aux2-1;
			}

		}
		if(nr0==p)
            out<<num;
			//fprintf(out,"%d",num);
		else
            out<<"-1";
		//	fprintf(out,"-1");
	}
	else
        out<<"-1";
		//fprintf(out,"1");

	return 0;
}