#include <bits/stdc++.h>
using namespace std;
int mini[1000005];
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    string a;
    cin>>a;
    int cnt = 0;
    for(int x=0;x<a.size();x++)
    {
        cnt++;
        if(a[x] == '1')
            cnt = 0;
        mini[x] = cnt;
    }
    cnt = 0;
    for(int x=a.size() - 1;x >= 0;x--)
    {
        cnt++;
        if(a[x] == '1')
            cnt = 0;
        mini[x] = min(mini[x], cnt);
    }
    int maks = 0;
    for(int x=0;x<a.size()-1;x++)
        maks = max(maks, mini[x]);
    cout<<maks;
    return 0;
}