#include <fstream>

using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int form(int n)
{
    int cnt=0,k=5;
    while(k<=n)
    {
        cnt=cnt+n/k;
        k=k*5;
    }
    return cnt;
}
int main()
{
    int p,n,i,nou,y;
    in>>p;
    if(p==0)
    out<<1;
    else
    {
        for(i=p*5; i>=p*4; i--)
        {
             y=form(i);

            if(form(i)==p)
            {
            nou=i;
            }
        }
        out<<nou;
    }
    return 0;
}