#include <iostream>
#include <fstream>
using namespace std;
long long n,nr=0,i=0,x;
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    f>>n;
    while (nr!=n)
    {
        i=i+5;
        nr++;
        x=i;
        while (x%25==0)
        {
            nr++;
            x=x/25;
        }
    }
    g<<i;
    return 0;
}