#include<fstream>
using namespace std;
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    
    long p,x,zero=0;
    
    f>>p;
    f.close();
    if(p==0)g<<"0";
    else
    
    for(int i=5;i<=900000000;i+=5)
    {
            x=i;
            while(x%5==0)
              {zero++;x/=5;}            
          if(zero>=p) {g<<i; break;}
          
                 
    }
    
    
return 0;    
}