#include<fstream>
using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int main() {
   int n,cnt=0,cnt1=0;long long int i;
   cin>>n;
   long long int j=1;
   for( i=j;;i=j)
   {
           while(i%2==0)
           {
               i/=2;
               cnt++;
           }
       while(i%5==0)
       { cnt1++;i/=5;}
       if(min(cnt,cnt1)>=n)
           break;
       j++;
   }
   cout<<j;

}