#include<stdio.h>
int main()
{
    int i,j,k,l,m,n,o,q,nr;
    long unsigned p;
    FILE *f; FILE *g;
    f=fopen("fact.in","r");
    g=fopen("fact.out","w");
    fscanf(f,"%lu",&p);
    if(p<0)
        fprintf(g,"%d",-1);
    if(p==0)
        fprintf(g,"%d",1);
    if(p==1)
       fprintf(g,"%d",5);
    if(p==2)
      fprintf(g,"%d",10); 
    if(p>2)
    {
fprintf(g,"%lu",5*p);


    }

return 0;
}