#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}());
const ll mod=998244353;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=5010000;
char ss[N];
int s[N],n,m;
vector<PII> v;
array<int,3> p[N];
int main() {	
	scanf("%s",ss);
	n=strlen(ss);
	rep(i,0,n) s[i+2]=ss[i]-'0';
	s[0]=s[1]=1; s[n+2]=s[n+3]=0;
	n+=4;
	ll ans=0;
	rep(i,0,n-1) if (s[i]==s[i+1]) {
		if (!v.empty()&&v.back().fi!=s[i]&&s[i]==1&&(i-v.back().se)%4==0) {
			ans+=(i-v.back().se)/4;
			v.pop_back();
		} else {
			v.pb(mp(s[i],i));
		}
	}
	rep(i,0,SZ(v)) {
		if (v[i].fi==1&&i>0&&v[i-1].fi==1) {
			int d=v[i-1].se+1;
			while (d%4!=v[i].se%4) ++d;
			ans+=(v[i].se-d)/4;
			v[i].se=d;
		}
	}
	per(i,0,SZ(v)) {
		if (v[i].fi==0&&i+1<SZ(v)&&v[i+1].fi==0) {
			int d=v[i+1].se-1;
			while (d%4!=v[i].se%4) --d;
			ans+=(d-v[i].se)/4;
			v[i].se=d;
		}
	}
	rep(i,0,SZ(v)) {
		int j=i;
		while (j+1<SZ(v)&&v[j+1].fi==v[i].fi) ++j;
		p[m++]={v[i].se,v[j].se,j-i+1};
		i=j;
	}
	assert(m%2==0);
	vector<ll> dp,pd;
	dp=vector<ll>{0};
	for (int i=1;i<m;i++) {
		pd=dp;
		dp.clear();
		if (i%2==1) {
			int rs=(i==m-1)?0:(p[i+1][0]-p[i][1]-2)/4;
			int ls=(p[i][0]-p[i-1][1]-2)/4;
			dp.resize(rs+1);
			rep(k,0,SZ(pd)) pd[k]+=(ll)k*(k+1)/2+(ll)ls*k;
			rep(j,0,rs+1) {
				for (int k:{0,SZ(pd)-1}) dp[j]=max(dp[j],pd[k]+(ll)j*k);
				dp[j]+=(ll)(j+ls)*(j+ls+1)/2+(ll)p[i][2]*j;
			}
		} else {
			int ls=(p[i][0]-p[i-1][1]-2)/4;
			dp.resize(ls+1);
			rep(j,0,ls+1) dp[j]=max(dp[j],
				(ll)p[i][2]*j+pd[ls-j]);
		}
	}
	printf("%lld\n",dp[0]+ans);
}