#include <fstream>

using namespace std;

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

int main()
{
    int p,n,pp,cp;
    in>>p;
    n=p*5;
    pp=n/25;
    cp=pp;
    while(pp)
    {
        n-=5;
        pp--;
        if(n/25<cp) pp--;
    }
    if(p==0) n++;
    out<<n;
    return 0;
}