#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
#define rep(i, n) for (int i = 0; i< (int)(n); i++) 

int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    string s; cin >> s;
    int len = s.length();
    int tmp = 0;
    ll t = 0;
    ll ans = 0;
    stack<int> st;
    int state = 0;
    for(int i = len -1 ; i >= 0; i--){
        if(s[i] == '0'){
            if(state == 0){
                tmp++;
            }else{
                tmp = 1;
                state = 0;
            }
        }else{
            if(state == 0){
                if(tmp > 0){
                    st.push(tmp);
                    t += tmp;
                }
                state = 1;
                tmp = 0;
            }else{
                ans += t;
                if(st.size() > 0){
                    t -= st.top();
                    tmp = st.top();
                    st.pop();
                }
                state = 0;
            }
        }
    }
    cout << ans << endl;
    return 0;
}