#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int main()
{
    int n,p,zero=0,cn;
    f>>p;
    n=1;
    while(zero<p)
    {
        n++;
        if(n%10==0)
        {
            cn=n;
            while(cn%10==0){zero++;cn/=10;}
        }
        if(n%10==5)
        {
            if(n%100==25)zero+=2;
              else zero++;
        }
    }
    g<<n;
    return 0;
}