#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);

	char c;
	vector<tuple<int, int, int, bool>> blocks;
	vector<tuple<int, int>> frees;
	int i = 0, n = 0;
	bool rfree = false;
	while (cin >> c) {
		c -= '0';
		if (rfree) {
			if (c > 0) {
				frees.push_back({n, c});
			}
		} else {
			blocks.push_back({i++, n, c, false});
		}
		rfree = !rfree;
		n += c;
	}

	for (auto &[fx, fn] : frees) {
		for (auto &[bi, bx, bn, bm] : blocks | views::reverse) {
			if (bm || bn > fn || bx < fx) {
				continue;
			}
			bx = fx;
			bm = true;
			fx += bn;
			fn -= bn;
		}
	}

	ull sum = 0;
	for (auto &[bi, bx, bn, bm] : blocks) {
		sum += (ull)bi * (bn * bx + bn * (bn - 1) / 2);
	}
	cout << sum << '\n';
}