#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <cmath>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#include <stdlib.h>
#include <stdio.h>
#include <bitset>
using namespace std;
#define FOR(I,A,B) for(int I = (A); I < (B); ++I)
typedef long long ll;
int slng, ans;
bool calc(string s) {
  int len = s.length();
  FOR (i,0,len/2) {
    if (s[i] != s[len-1-i]) {
      return false;
    }
  }
  return true;
}
void dfs(string s, int MAX) {
  if(s[0] == 'a') {
    if (MAX != slng) ans = max(ans, MAX);
    return;
  }
  FOR(i,0,s.length()){
    if(calc(s.substr(0,i+1))){
      dfs(s.substr(i+1), max(MAX, i+1));
    }
  }
  return;
}
int main(){
  string s;
  cin >> s;
  slng = s.length();
  s += 'a';
  ans = 0;
  dfs(s,0);
  cout << ans << endl;
  return 0;
}