#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#define p(s) cout<<(s)<<endl
#define REP(i,n,N) for(int i=n;i<N;i++)
#define RREP(i,n,N) for(int i=N-1;i>=n;i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define F first
#define S second
typedef long long ll;
using namespace std;
const ll mod = 1e9+7;

string s;
int ans;
int main() {
    cin>>s;
    int n = s.size();
    ans = 1;
    REP(l,0,n){
        REP(r,l+1,n){
            int a=0;
            REP(i,0,(r-l+1)/2){
                if(s[l + i]!=s[r - i]){
                    a+=2;
                }
            }
            ans = max(ans, (r-l+1) - a);
        }
    }

    p(ans);
    return 0;
}