Takahashi has an empty string S and a variable x whose initial value is 0.

Also, we have a string T consisting of `0` and `1`.

Now, Takahashi will do the operation with the following two steps |T| times.

* Insert a `0` or a `1` at any position of S of his choice.
* Then, increment x by the sum of the digits in the odd positions (first, third, fifth, ...) of S. For example, if S is `01101`, the digits in the odd positions are `0`, `1`, `1` from left to right, so x is incremented by 2.



Print the maximum possible final value of x in a sequence of operations such that S equals T in the end.

Constraints

* 1 \leq |T| \leq 2 \times 10^5
* T consists of `0` and `1`.

Input

Input is given from Standard Input in the following format:


T


Output

Print the maximum possible final value of x in a sequence of operations such that S equals T in the end.

Examples

Input

1101


Output

5


Input

0111101101


Output

26
#include <bits/stdc++.h>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl;
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
typedef long long ll;
#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(int)(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a = b; return 1; } return 0; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
#define Sp(p) cout<<setprecision(25)<< fixed<<p<<endl;
//int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
//int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
vi dx2 = { 1,1,0,-1,-1,-1,0,1 }, dy2 = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'


signed main() {
    fio();
    string t;
    cin >> t;
    ll ans = 0;
    int n = t.size();
    ll ki = 0;


    rep (i, n) {
        if (t[i] == '1') {
            ki++;
        }
    }
    rep1 (i, ki) {
        ans += (i + 1) / 2;
    }

    int m = n - ki;
    string s;
    string t2;
    ki = 0;
    // DEBUG(ans);
    // DEBUG(m);
    rep (i, n) {
        if (t[i] == '0') {
            s.push_back('0');
        }
        else {
            if (s.size() > 0 and s.back() == '1') {
                ans += m;
                s.pop_back();
                ki--;
            }
            else {
                s.push_back('1');
                ki++;
            }
        }
    }
    // DEBUG(s);
    // DEBUG(ans);

    int l1 = 0, l0 = 0, r1 = (ki + 1) / 2;
    int r0 = ki - r1;
    n = s.size();
    vector<bool> used(n);
    rep (i, n) {
        if (s[i] == '1') used[i] = true;
        if (i > 0 and s[i - 1] == '1') {
            assert(s[i] == '0');
            l1++;
            r1--;
            swap(r1, r0);
            used[i] = true;
            ans += l1 + r1;
        }
    }
    if (s.back() == '1') {
        l1++;
        r1--;
    }
    // DEBUG(ans);
    // DEBUG_VEC(used);
    // DEBUG_VEC(vi({l0, l1, r0, r1}));

    rrep (i, n) {
        if (s[i] == '1') {
            l1--;
            r1++;
        }
        else {
            if (used[i]) continue;
            swap(r0, r1);
            ans += l1 + r1;
        }
    }
    cout << ans << endl;
}