#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; 
}} 
return 0; 
}