#include <fstream>
using namespace std;
ifstream f("factorial.in");
ofstream g("factorial.out");
int main()
{
    int n,i,s=1,x,nr=0,p,c,numar=1,final=0;
    f>>p;
    for(i=1;i<=1000;i++)
    {
        s=s*i;
        x=s;
        final++;
        while(x!=0)
        {
            c=x%10;
            if(c==0)
                nr++;
            x=x/10;
        }
        if(nr==p)
           break;
        else
            nr=0;
    }
    g<<i;
    return 0;
}