#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long
#define all(x) (x).begin(),(x).end()
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b;return true;}return false;}
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

int main() {
    int N;
    cin >> N;
    cout << N /3 << endl;
}
#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ll long long
#define all(x) (x).begin(),(x).end()
template<class T> inline bool chmax(T& a, T b) {if (a < b) {a = b;return true;}return false;}
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
const int INF = 1000000000;

int main() {
    string s;
    cin >> s;
    if (s.size() == 2)cout << s << endl;
    else {
        reverse(all(s));
        cout << s << endl;
    }
}