#pragma option -3 -r -Z -O2 -a
#include<fstream.h>
int main()
{unsigned long gen,x,i;
long p;
ifstream f("fact.in");
f>>p;
f.close();
ofstream g("fact.out");
if(p==0){g<<"1"<<'\n';g.close();return 0;}
 else if((p<0)||(p>100000000)){g<<"-1"<<'\n';g.close();return 0;}
i=p;
gen=5;
while(i)
  {x=gen;
   x=x/5;i--;
   while(((x%5)==0)&&(i)){i--;x=x/5;}
   gen+=5;
  }
g<<gen-5<<'\n';
g.close();
return 0;
}