#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
using pi = pair< int, int >;


int main() {
  string s;
  cin >> s;
  int ret = 0;
  for(int i = 0; i < s.size(); i++) {
    {
      int j = i - 1, k = i + 1, match = 0;
      while(j >= 0 && k < s.size() && s[j] == s[k]) {
        match += 2;
        --j;
        ++k;
      }
      ret = max(ret, match);
    }
    if(i - 1 >= 0) {
      int j = i - 2, k = i + 1, match = 1;
      while(j >= 0 && k < s.size() && s[j] == s[k]) {
        match += 2;
        --j;
        ++k;
      }
      ret = max(ret, match);
    }
    if(i + 1 < s.size()) {
      int j = i - 1, k = i + 2, match = 1;
      while(j >= 0 && k < s.size() && s[j] == s[k]) {
        match += 2;
        --j;
        ++k;
      }
      ret = max(ret, match);
    }
  }
  cout << ret << endl;
}