#include<cstdio>
using namespace std;
FILE *f,*g;
int nr0,i,x,n;
int main()
{f=fopen("fact.in","r");
g=fopen("fact.out","w");
fscanf(f,"%d",&n);
if(n==0)
	fprintf(g,"1\n");
else
{i=4*n;
while(i%5!=0)
	++i;
while(nr0<n)
{nr0=0;
x=i;
while(x!=0)
{nr0=nr0+x/5;;
x=x/5;
}
if(nr0>n)
{fprintf(g,"-1\n");
break;
}
else
	if(nr0==n)
	{fprintf(g,"%d\n",i);
	break;
	}
i=i+5;
}}
fclose(f);
fclose(g);
return 0;
}