#include <fstream>

using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main()
{
    int a,nr=0,x,c;
    fin >>x;
    a=0;
    while (nr<=x)
    {
        a=a+5;
        c=a;
        while (c%5==0)
        {
            nr++;
            c=c/5;
        }

        if (nr==x) break;
    }
    if (x!=0) fout <<a;
    else fout<<"1";
    return 0;
}