#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <sstream>
#include <complex>
#include <ctime>
#include <cassert>
#include <functional>

using namespace std;

typedef long long ll;
typedef vector<int> VI;
typedef pair<int,int> PII;

#define REP(i,s,t) for(int i=(s);i<(t);i++)
#define FILL(x,v) memset(x,v,sizeof(x))
#define MAXN 5005

int n, ans;
string s;

void solve(int l, int r, int ml) {
  bool haslr = l >= 0 && r < n;
  bool mismatch = !haslr || s[l] != s[r];
  if (!mismatch) {
    solve(l - 1, r + 1, ml);
    return;
  }
  if (ml == -1) {
    ans = max(ans, r - l - 1);
    if (haslr) solve(l - 1, r + 1, l);
    return;
  }
  else if (ml == -2) {
    ans = max(ans, r - l - 1);
    return;
  }
  else {
    int mr = r - (ml - l);
    if (haslr && ((s[ml] == s[r] && s[mr] == s[l]) || (s[ml] == s[l] && s[mr] == s[r]))) {
      solve(l - 1, r + 1, -2);
    }
    else {
      ans = max(ans, mr - ml - 1);
      REP(i,1,n+1) {
        int cl = ml - i, cr = mr + i;
        if (cl <= l || cr >= r) break;
        if (s[cl] == s[ml] || s[cr] == s[ml] || s[cl] == s[mr] || s[cr] == s[mr]) {
          ans = max(ans, cr - cl - 1);
        }
      }
      VI cands;
      REP(i,0,n) if (i <= l || i >= r) cands.push_back(i);
      if ((mr - ml) % 2 == 0) cands.push_back((ml + mr) / 2); // don't forget center!
      for (auto i: cands) {
        if (s[i] == s[ml] || s[i] == s[mr]) {
          ans = max(ans, r - l - 1);
        }
      }
    }
  }
}
int main() {
  cin >> s;
  n = s.size();
  ans = 1;
  REP(i,0,n) {
    solve(i - 1, i + 1, -1);
    solve(i, i + 1, -1);
  }
  cout << ans << endl;
  return 0;
}