#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
ll inf_ll = 9223372036854775807;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
using mint = atcoder::modint998244353;
using mint1 = atcoder::modint1000000007;
using Pa = std::pair<ll, ll>;

int Yes(bool x){
    if(x) cout << "Yes";
    else cout << "No";
    cout << endl;
    return 0;
}

ll solve(deque<Pa> &A){
    if(A.size() < 2){
        return 0;
    }
    auto [a, b] = A.front();
    A.pop_front();
    if(a == 0){
        return solve(A);
    }
    auto [c, d] = A.front();
    A.pop_front();
    if(A.size() == 0){
        return (b / 2) * d;
    }
    auto [e, f] = A.front();
    A.pop_front();
    A.push_front({e, f+(b/2)*2});
    ll x = (b/2)*d;
    x += solve(A);
    return x;
}

int main(){
    string S;
    cin >> S;
    ll N = S.size();
    deque<Pa> A;
    ll x = 0;
    rep(i, N){
        if(i == 0 || S[i-1] == S[i]){
            x++;
        }
        else{
            A.push_back({S[i-1]-'0', x});
            x = 1;
        }
    }
    A.push_back({S[N-1]-'0', x});
    cout << solve(A);
}