#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int main()
{
    int p,n,ni=0,r=2;
    f>>p;
    if(p==0)g<<1;
    else
    {
        p--;
        for(n=5;p!=0;n+=5)
        {
            if(n%25==0){
                p-=r;
                r++;}
            else
                p--;
        }
        g<<n;
    }
}