#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
using ul = unsigned long long;
using ll = long long;
using ld = long double;
using pll = pair<ll,ll>;
#define in(v,c) ((c).find(v) != (c).end())
#define F(i,n) for(ll i = ; i < (n); i++)
#define Fun(i,n) for(ul i = ; i < (n); i++)
#ifdef GPD
template<class F>void lerr(F&&f){cerr<<forward<F>(f)<<endl;}
template<class F,class...R>void lerr(F&&f,R&&...r){cerr<<forward<F>(f)<<' ';lerr(forward<R>(r)...);}
#else
#define lerr(...)
#endif

char arr [300007];
ll pref [300007];
ll suff [300007];

int main(int argc, char const *argv[]) {
    cin.tie(0)->sync_with_stdio(0);
    cout << setprecision(9) << fixed; lerr("ready");
    ll n = 0;
    while(!cin.eof()){
        cin >> arr[n];
        ++n;
    }

    ll count  = 999999999;
    for(ll i = 0; i < n; ++i){
        if(arr[i] == '1'){
            count = 0;
        }
        pref[i] = count; 
        ++count;
    }

    count  = 999999999;
    for(ll i = n-1; i >= 0; --i){
        if(arr[i] == '1'){
            count = 0;
        }
        suff[i] = count; 
        ++count;
    }
    ll acc = 0;
    for(ll i = 0; i < n; ++i){
        ll tmp = min(pref[i], suff[i]);
        acc = max(acc, tmp);
    } 
    cout << acc << endl;
    return 0;
}