Divide3

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

#define int long long
#define inf 2e18
int MOD=1000000007;//998244353;
const int nn=1000050;
bool prime[nn]; //array to store precalculated primes till 10^6
void cal_primes(){memset(prime,true,sizeof(prime)); for(int i=2;i<=sqrt(nn);++i){ if(prime[i]==true){ for(int j=i*i;j<=nn;j+=i){prime[j]=false;}}}}

void solve(int t)
{
    int testcases=t;
    while(t--)
    {
        string s;cin>>s;
        int n=s.length(),ans=0,len=0,c0=0,c1=0;
        vector<pair<char,int>>v;
        for(int i=0;i<n;i++)
        {
            if(s[i]=='0')
            {
                if(c1>0)
                    v.push_back(make_pair('1',c1)),c1=0;
                c0++;
            }
            else
            {
                if(c0>0)
                    v.push_back(make_pair('0',c0)),c0=0;
                c1++;
            }
        }
        if(c1>0)
            v.push_back(make_pair('1',c1)),c1=0;
        else
            v.push_back(make_pair('0',c0)),c0=0;

        // for(auto it:v)
        //  cout<<it.first<<" "<<it.second<<endl;

        for(int i=0;i<v.size();i++)
        {
            ans=0;
            if(v[i].first=='1')
            {
                ans+=v[i].second;
                if(i!=0)
                    ans+=v[i-1].second;
                if(i!=(v.size()-1))
                    ans+=v[i+1].second;
            }
            else
                ans+=v[i].second;

            len=max(len,ans);
        }
        cout<<len<<endl;
    }
}

main()
{
    auto start=chrono::system_clock::now();
    {
        #ifndef ONLINE_JUDGE
            freopen("input.txt","r",stdin);
            freopen("output.txt","w",stdout);
            freopen("error.txt","w",stderr);
        #endif
        ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
        int t=1;
    //  cin>>t;
        solve(t);
    }
    auto end=chrono::system_clock::now();
    chrono::duration<double> elapsed=end-start;
//  cout<<endl<<"Time taken: "<<elapsed.count()<<" sec";
    return 0;
}