#include <fstream>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

int main()
{
int x=5,cx,i,n,nr0=0;

f>>n;

while(nr0<n)
{
    cx=x;
    while(cx%5==0 and nr0<n)
        cx/=5,nr0++;
    x+=5;
}

if(nr0==0)
    g<<1;
else g<<x-5;
    return 0;
}