#include <iostream>
#include <fstream>
#define MAX 1000

using namespace std;

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

int P;

int main()
{
    in>>P;
    if(P == 0){
        cout<<1;
        out<<'1';
        return 0 ;
    }
    for(int i = 0 ; i < MAX; i ++){
        int a = i/5;
        if(a == P){
            if(i % 25 == 0){
                out<<i-5;
                return 0;
            }
            out<<i;
            return 0;
        }
    }


}