#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define rep(i,s,e) for(int (i) = (s);(i) <= (e);(i)++)

string s;
int main(){
  cin >> s;
  int ans = 0;
  rep(cen,0,s.size() - 1){
    int left = cen - 1;
    int right = cen + 1;
    int len = 1;
    while(left >= 0 && right < s.size()){
      if(s[left] == s[right]){
        len+=2;
      }
      left--;
      right++;
    }
    ans = max(ans,len);
    left = cen;
    right = cen + 1;
    len = 0;
    while(left >= 0 && right < s.size()){
      if(s[left] == s[right]){
        len+=2;
      }
      left--;
      right++;
    }
    ans = max(ans,len);
  }

  cout << ans << endl;
}