//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,avx512f")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>
#include <cassert>
#include <memory>
#include <random>
#include <functional>
#include <complex>
#include <immintrin.h>
#ifdef DEBUG
#include "./Lib/debug_VC.hpp"
#include "./Lib/Timer.hpp"
#include "./Lib/sample.hpp"
#else
#define dump(...)
#endif

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
template<class T>
inline auto sort(T& t) { std::sort(ALL(t)); }
template<class T>
inline auto rsort(T& t) { std::sort((t).rbegin(), (t).rend()); }
template<class T>
inline auto unique(T& t) { (t).erase(unique((t).begin(), (t).end()), (t).end()); }
template<class T, class S>
inline auto chmax(T& t, const S& s) { if (s > t) { t = s; return true; } return false; }
template<class T, class S>
inline auto chmin(T& t, const S& s) { if (s < t) { t = s; return true; } return false; }
inline auto BR() { std::cout << "\n"; }

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;
template<class T>
using V = std::vector<T>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* Remove the source of the bug */
signed pow(signed, signed) { assert(false); return -1; }

/* define hash */
namespace std {
template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } };
}

/* input */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }

/* constant value */
constexpr ll MOD = 1000000007;
//constexpr ll MOD = 998244353;

//=============================================================================================;

auto solve(const string& s) {
	ll n = s.size();

	VL bb(n);
	bool go = true;
	REP(i, n) {
		if (i - 1 >= 0) { bb[i] = bb[i - 1]; }
		if (!go) { go = true; continue; }
		if (go && s[i] == '1') {
			++bb[i];
			go = false;
		}
	}

	ll ans = 0;
	ll od = 0;
	ll ev = 0;
	REP(i, n) {
		ll ad = 0;
		if (s[i] == '0') {
			ad = bb[i];
		} else {
			ll l = (i / 2) + 1;
			ad = l;
		}
		ans += ad;
		//dump(ad);
	}
	//dump(bb);
	return ans;
}

auto solve_c(const string& s) ->ll {
	static unordered_map<string, ll> mp;
	if (s.size() == 0) { return 0LL; }
	if (mp.find(s) != mp.end()) { return mp[s]; }

	ll ans = 0;
	REP(i, s.size())if (!(i & 1) && s[i] == '1') { ++ans; }
	//dump(s, ans);

	ll tmp = 0;
	REP(i, s.size()) {
		string t = s.substr(0, i) +
			s.substr(i + 1, s.size() - i - 1);
		chmax(tmp, solve_c(t));
	}
	ans += tmp;
	mp.emplace(s, ans);
	return ans;
}

signed main() {
	/**/
	string s;
	cin >> s;

	auto ans = solve(s);
	cout << ans << endl;

	//auto ans_c = solve_c(s);
	//dump(ans_c);
	/*/
	auto gen = Sample::SampleGenerator();
	REP(_, 100) {
		auto [n] = gen.generate(PAIR{3,8});
		auto [v] = gen.generate(V<PAIR>(n, PAIR{0,1}));
		string s = "";
		REPC(x, v) {
			s += (x == 0) ? '0' : '1';
		}

		auto ans = solve(s);
		auto ans_c = solve_c(s);
		if (ans != ans_c) {
			cout << s << endl;
			dump(ans, ans_c);
			return 0;
		}
	}
	/**/
}

Measured memory_bytes: 5212