#include<stdio.h>
#include<math.h>

long put(long n)
{
 long k=0;
 while(n%5==0) { k++; n/=5; }
 return k;
}

int main(void)
{
 long t,n,i,s,x=5;
 freopen("fact.in","r",stdin);
 freopen("fact.out","w",stdout);
 scanf("%ld",&n);
 while(1)
 {
  for(i=1,s=0; s<n,x>=pow(5,i); i++) s+=x/pow(5,i);
  if(s==n) { printf("%ld",x); break; }
      else x+=5;
 }
 return 0;
}