#include<fstream>
using namespace std;
long long p,n=1,m=5,k,x,z,y;
int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
    if(!p){fout<<1;return 0;}
  do
  {
      x++;n=5*x;y=x;z=0;
      while(!(y%5))y/=5,z++;
     if(!z)k++;else
     if(z==1)k+=2;else
     if(z==2)k+=3;else
     if(z==3)k+=4;else
     if(z==4)k+=5;




  }while(k!=p);
  fout<<n;
    return 0;
}