#include<bits/stdc++.h>
#define ll long long
using namespace std;
int n,one,five = -1,eleven = -1;
int main(){
    cin >> n;
    one = n;
    while(n >= 0){
        five++;
        n -= 5;
    }
    n += 5,five += n,n = one;
    while(n >= 0){
        eleven++;
        n -= 11;
    }
    n += 11;
    while(n >= 0){
        eleven++;
        n -= 5;
    }
    n += 5,eleven -= 1;eleven += n;
    cout << min(eleven,min(one,five)) << endl;
    return 0;
}