#include <bits/stdc++.h>

#define tle ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
#define ll long long
#define ld long double
#define sz(a) (int)(a.size())

using namespace std;
const int N = 2e5 + 5, M = 475260;
const int INF = 0x3f3f3f3f;
const int mod = 1e9 + 7;
ld EPS = 1e-5;


vector<int> manacher_algo(string s) {

    int n = s.size();

    vector<int> d0(n, 0);
    for (int i = 0, l = 0, r = -1; i < n; i++) {
        d0[i] = (i <= r) ? (min(d0[r - i + l + 1], r - i + 1)) : 0;
        while (i + d0[i] < n && i - d0[i] - 1 >= 0 && s[i + d0[i]] == s[i - d0[i] - 1])
            d0[i]++;
        if (i + d0[i] - 1 > r) {
            r = i + d0[i] - 1;
            l = i - d0[i];
        }
    }
    return d0;
}


int main() {
    tle
    string s;
    cin >> s;
    int n = s.size();
    auto man = manacher_algo(s);
    vector<int> mxpal(n);
    for (int i = 0; i < n; ++i) {
        int index = i - man[i] ;
        if(index<0)continue;
        mxpal[index] = max(mxpal[index], man[i]);
    }
    for (int i = 1; i < n; ++i)
        mxpal[i] = max(mxpal[i], mxpal[i - 1] - 1);
    int lastindex=0;
    while (mxpal[lastindex]>0)
        lastindex+=mxpal[lastindex];
    s=s.substr(lastindex);


    n = s.size();
    man = manacher_algo(s);
    vector<int> mxpal2(n);
    for (int i = n-1; i >=0; --i) {
        int index = i + man[i]-1;
        if(index > n-1)continue;
        mxpal2[index] = max(mxpal2[index], man[i]);
    }
    for (int i = n-2; i >=0; --i)
        mxpal2[i] = max(mxpal2[i], mxpal2[i + 1] - 1);
    lastindex=n-1;
    while (mxpal2[lastindex]>0)
        lastindex-=mxpal2[lastindex];
    cout<< lastindex+1;



}