//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
struct segment
{
	int lpos,rpos,cnt;
	ll sum;
	bool type;
	segment():sum(-1){}
	segment(int _lpos,int _rpos,int _cnt,ll _sum,bool _type):
		lpos(_lpos),rpos(_rpos),cnt(_cnt),sum(_sum),type(_type){}
};
ll calc(int cnt,int pos)
{
	int r=(cnt-1)*4+pos;
	return 1ll*(r+pos)*cnt/2;
}
ll dp[5005000][2];
ll total[5005000];
int main()
{
	// freopen("schrodingerszomb12.in","r",stdin);
	// freopen("out.txt","w",stdout);
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	for(int i=5;i<5005000;i++)
	{
		int x=(i-1)/4*4;
		total[i]+=x;
		total[i]+=total[x-1];
	}
	int t=1;
	while(t--)
	{
		string s;
		cin>>s;
		s="1"+s+"0";
		int n=sz(s);
		vector<pii> vec;
		for(int i=1;i<n;i++)
			if(s[i]==s[i-1])
				vec.pb(s[i]^48,i);
		// for(auto pr:vec)
		// 	cerr<<"? "<<pr.first<<" "<<pr.second<<endl;
		vector<pii> tmp;
		ll ssum=0;
		for(auto pr:vec)
			if(!sz(tmp)||pr.first==0||tmp.back().first==1||(pr.second-tmp.back().second)%4)
				tmp.pb(pr);
			else
			{
				ssum+=pr.second-tmp.back().second;
				tmp.pop_back();
			}
		swap(tmp,vec);
		// for(auto pr:vec)
		// 	cerr<<"? "<<pr.first<<" "<<pr.second<<endl;
		vector<pii> vec2;
		vector<int> vb;
		vb.pb(0);
		for(int i=1;i<sz(vec);i++)
			if((vec[i].second-vec[i-1].second)%4)
				vb.pb(i);
		vb.pb(sz(vec));
		vector<segment> cur;
		auto add=[&](int cnt,int pos,ll sum,bool type)->void
		{
			// cerr<<"! "<<cnt<<" "<<pos<<" "<<sum<<" "<<type<<endl;
			if(!sz(cur)||cur.back().type!=type)
			{
				cur.pb(pos,pos+(cnt-1)*4,cnt,sum,type);
				return ;
			}
			if(!type)
			{
				int rpos=cur.back().rpos;
				int need=(pos-rpos-1)/4;
				pos-=need*4;
				sum-=4ll*cnt*need;
				cur.back().rpos=pos+(cnt-1)*4;
				cur.back().cnt+=cnt;
				cur.back().sum+=sum;
			}
			else
			{
				int need=(pos-cur.back().rpos-1)/4;
				cur.back().lpos+=need*4;
				cur.back().rpos=pos+(cnt-1)*4;
				cur.back().sum+=sum+4ll*cur.back().cnt*need;
				cur.back().cnt+=cnt;
			}
		};
		for(int i=1;i<sz(vb);i++)
		{
			int l=vb[i-1],r=vb[i]-1;
			// cerr<<"& "<<l<<" "<<r<<endl;
			int cnt0=(r-l+1)/2,cnt1=(r-l+1)/2;
			if((r-l+1)%2)
			{
				if(vec[l].first)
					cnt1++;
				else
					cnt0++;
			}
			if(cnt1)
				add(cnt1,vec[l].second,calc(cnt1,vec[l].second),0);
			if(cnt0)
				add(cnt0,vec[r].second,calc(cnt0,vec[r].second-4*cnt0+4),1);
		}
		// for(auto seg:cur)
		// 	cerr<<seg.cnt<<" "<<seg.sum<<" "<<seg.lpos<<" "<<seg.rpos<<" "<<seg.type<<endl;
		// cerr<<endl;
		for(int i=0;i<=sz(cur)+10;i++)
			dp[i][0]=dp[i][1]=-0x3f3f3f3f3f3f3f3f;
		dp[0][0]=0;
		vector<pair<segment,segment>> parts;
		for(auto seg:cur)
			if(seg.type)
			{
				if(!sz(parts)||~parts.back().second.sum)
					parts.pb(segment(),seg);
				else
					parts.back().second=seg;
			}
			else
			{
				if(!sz(parts)||~parts.back().first.sum||~parts.back().second.sum)
					parts.pb(seg,segment());
				else
					parts.back().first=seg;
			}
		for(int i=0;i<sz(parts);i++)
		{
			auto pr=parts[i];
			if(pr.first.sum==-1)
			{
				assert(i==0);
				ll val=max(dp[i][0],dp[i][1]);
				val+=pr.second.sum;
				int len=pr.second.lpos-1;
				if(len>4)
				{
					int cnt=(len-1)/4;
					cnt=(cnt+1)/2;
					ll R=len-1,L=R-cnt*8;
					val+=(L+R)*cnt/2;
				}
				dp[i+1][0]=max(dp[i+1][0],val);
				int rbound=n-1;
				if(i!=sz(parts)-1)
					rbound=parts[i+1].first.lpos-1;
				int mv=(rbound-pr.second.rpos)/4;
				pr.second.lpos+=mv*4;
				pr.second.sum+=4ll*pr.second.cnt*mv;
				val=max(dp[i][0],dp[i][1]);
				val+=pr.second.sum;
				len=pr.second.lpos-1;
				// cerr<<"! "<<len<<endl;
				if(len>4)
					val+=total[len];
				dp[i+1][1]=max(dp[i+1][1],val);
			}
			else if(pr.second.sum==-1)
			{
				assert(i==sz(parts)-1);
				{
					ll val=dp[i][1];
					val-=pr.first.sum;
					int len=n-pr.first.rpos;
					if(len>4)
						val+=total[len];
					dp[i+1][1]=max(dp[i+1][1],val);
				}
				{
					ll val=dp[i][0];
					int lbound=1;
					if(i)
						lbound=parts[i-1].second.rpos+1;
					int mv=(pr.first.lpos-lbound)/4;
					pr.first.sum-=4ll*pr.first.cnt*mv;
					pr.first.rpos-=4*mv;
					val-=pr.first.sum;
					int len=n-pr.first.rpos;
					if(len>4)
						val+=total[len];
					dp[i+1][1]=max(dp[i+1][1],val);
				}
			}
			else
			{
				for(int a=0;a<2;a++)
					for(int b=0;b<2;b++)
					{
						int mvl=0,mvr=0;
						if(!a)
						{
							int lbound=1;
							if(i)
								lbound=parts[i-1].second.rpos+1;
							mvl=(parts[i].first.lpos-lbound)/4;
						}
						if(b)
						{
							int rbound=n-1;
							if(i!=sz(parts)-1)
								rbound=parts[i+1].first.lpos-1;
							mvr=(rbound-parts[i].second.rpos)/4;
						}
						ll val=dp[i][a]-(pr.first.sum-4ll*mvl*pr.first.cnt)+(pr.second.sum+4ll*mvr*pr.second.cnt);
						int len=(pr.second.lpos-pr.first.rpos-1);
						len+=(mvl+mvr)*4;
						if(len>4)
							val+=total[len];
						dp[i+1][b]=max(dp[i+1][b],val);
					}
			}
			// cerr<<dp[i+1][0]<<" "<<dp[i+1][1]<<endl;
		}
		ll tot=0;
		for(auto pr:vec)
			if(pr.first)
				tot+=pr.second;
			else
				tot-=pr.second;
		cout<<(dp[sz(parts)][1]+tot+ssum)/4<<'\n';
	}
	return 0;
}