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

using namespace std;

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

//5 10 15 20 25
int P;
int zece(int k){
    return k/10;
}
int cinci(int k){
    return k/5-zece(k);
}
int all(int k){
    return zece(k) + cinci(k);
}

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

        }
        if(a == P){
            out<<best+i;
            return 0;
        }


    }



}