#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef double ld;
//#define ll __int128
//#define int ll
//#define int ll
//#define char ll
#define double ld
typedef vector<char> vc;
typedef vector<vc> vvc;
typedef vector<vvc> vvvc;
typedef pair<int, int> pii;
typedef pair<pii, pii> piii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector<vi> vvi;
typedef vector<vvi> vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < int(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";


template<class T0, class T1>
inline ostream &operator<<(ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template<class T0, class T1>
inline istream &operator>>(istream &in, pair<T0, T1> &a) {
    return in >> a.first >> a.second;
}

template<class T0, class T1, class T2>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template<class T0, class T1, class T2, class T3>
inline ostream &operator<<(ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << ", " << get<3>(a) << "}";
}

template<class T>
inline ostream &operator<<(ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}


void smain();


signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
#ifdef MAX_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    cout << setprecision(12) << fixed;
    smain();
#ifdef MAX_HOME
    cout << "\n\nTOTAL EXECUTION TIME: " << float(clock() - start) / CLOCKS_PER_SEC << endl;
#endif
    return 0;
}

int get(string s, vi p) {
    int n = s.size();
    vector<bool> used(n, false);
    int cur = 0;
    for (auto pos : p) {
        used[pos] = true;
        string t = "";
        fori (i, n) if (used[i])
                t += s[i];

        for (int i = 0; i < SZ(t); i += 2) {
            cur += t[i] == '1';
        }
    }
    return cur;
}

int kek(string s) {
    int n = SZ(s);

    bool odd = false;
    vi p1, p2, p3;
    fori (i, n) {
        if (s[i] == '1') {
            p1.push_back(i);
            odd ^= 1;
        } else {
            if (odd) {
                p2.push_back(i);
                odd = false;
            } else {
                p3.push_back(i);
            }
        }
    }
    reverse(ALL(p3));
    p1.insert(p1.end(), ALL(p2));
    p1.insert(p1.end(), ALL(p3));
    return get(s, p1);
}

int naive(string s) {
    int n = s.size();
    vi p(n);
    fori (i, n) {
        p[i] = i;
    }
    int ans = -1;
    vi best = p;
    do {
        int cur = get(s, p);
        if (cur > ans) {
            ans = cur;
            best = p;
        }
        if (cur == 26)
            break;
    } while (next_permutation(ALL(p)));
//    watch(best);
    return ans;
}

void stress() {
    int cnt = -1;
    while (true) {
        if (++cnt % 2000 == 0)
            watch(cnt);
        int n = 1 + rng() % 10;
        string s(n, '0');
        fori (i, n) {
            s[i] = char('0' + rng() % 2);
        }
        if (naive(s) != kek(s)) {
            watch(s);
            return;
        }
    }
}

struct Tree {
    vector<pii> t;
    vi cnt;
    vector<int> pushing;
    Tree(int n) {
        t.resize(n << 2, {0, 0});
        pushing.resize(n << 2, false);
        cnt.resize(n << 2, 0);
    }

    void push(int v) {
        if (pushing[v]) {
            swap(t[v << 1].first, t[v << 1].second);
            swap(t[v << 1 | 1].first, t[v << 1 | 1].second);
            pushing[v << 1] ^= pushing[v];
            pushing[v << 1 | 1] ^= pushing[v];
            pushing[v] = false;
        }
    }

    void upd(int v, int tl, int tr, int pos, int val, bool odd) {
        cnt[v]++;
        if (tl == tr) {
            if (odd)
                t[v].second = val;
            else
                t[v].first = val;
            return;
        }
        push(v);
        int tm = tl + tr >> 1;
        if (pos <= tm)
            upd(v << 1, tl, tm, pos, val, odd);
        else
            upd(v << 1 | 1, tm + 1, tr, pos, val, odd);
        t[v].first = t[v << 1].first + t[v << 1 | 1].first;
        t[v].second = t[v << 1].second + t[v << 1 | 1].second;
    }

    void swp(int v, int tl, int tr, int l, int r) {
        if (l > r)
            return;
        if (tl == l && tr == r) {
            swap(t[v].first, t[v].second);
            pushing[v] ^= 1;
            return;
        }
        push(v);
        int tm = tl + tr >> 1;
        swp(v << 1, tl, tm, l, min(tm, r));
        swp(v << 1 | 1, tm + 1, tr, max(tm + 1, l), r);
        t[v].first = t[v << 1].first + t[v << 1 | 1].first;
        t[v].second = t[v << 1].second + t[v << 1 | 1].second;
    }

    int get_cnt(int v, int tl, int tr, int l, int r) {
        if (l > r)
            return 0;
        if (tl == l && tr == r)
            return cnt[v];
        push(v);
        int tm = tl + tr >> 1;
        return get_cnt(v << 1, tl, tm, l, min(tm, r)) +
            get_cnt(v << 1 | 1, tm + 1, tr, max(tm + 1, l), r);
    }
};

ll fast_get(string s, vi p) {
    int n = s.size();
    Tree tree(n);
    ll ans = 0;
    for (auto pos : p) {
        tree.upd(1, 0, n - 1, pos, s[pos] == '1', tree.get_cnt(1, 0, n - 1, 0, pos) & 1);
        tree.swp(1, 0, n - 1, pos + 1, n - 1);
        ans += tree.t[1].first;
    }
    return ans;
}

ll fast_kek(string s) {
    int n = SZ(s);

    bool odd = false;
    vi p1, p2, p3;
    fori (i, n) {
        if (s[i] == '1') {
            p1.push_back(i);
            odd ^= 1;
        } else {
            if (odd) {
                p2.push_back(i);
                odd = false;
            } else {
                p3.push_back(i);
            }
        }
    }
    reverse(ALL(p3));
    p1.insert(p1.end(), ALL(p2));
    p1.insert(p1.end(), ALL(p3));
    return fast_get(s, p1);
}

void smain() {

//    stress();
//    return;


    string s;
    cin >> s;
    cout << fast_kek(s) << '\n';
//    watch(naive(s));

}

Measured memory_bytes: 18836