#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int main()
{
    int a[15],i,p=1,nr=0,k,x,y;
    for(i=1;i<=14;++i)
        a[i]=p*=5;
    fin>>p;if(!p)fout<<1;else{
    y=5;
    while(nr!=p)
    {
        x=y;
        for(i=14;i>=1;--i)
            while(!(x%a[i]))
            {
                x/=a[i];
                nr+=i;
            }
        y+=5;
    }
    fout<<y-5;}
}