#include <fstream.h>
int main(){
	unsigned long p,k,i,aux,ok;
	ifstream f("fact.in");
	ofstream g("fact.out");
	f>>p;
	if(p>0){
		i=0;ok=0;
		if(p>100){
			i=25;
			while(p>100){
				aux=i;
				while(aux%25==0){
					aux/=25;p-=4;
				}
				if(aux==5)ok=1;
				i+=25;
			}
		}
			if(!i)i=5;
			else
				i-=25;
			k=0;
			while(k<p){
				aux=i;
				while(aux%5==0){
					aux/=5;k++;
				}
				i+=5;
			}
		if(k==p&&!ok)
			g<<i-5;
		else
			g<<-1;
	}else
		g<<1;
	f.close();
	g.close();
	return 0;

}