#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    string S;
    cin >> S;
    int ans = 0;
    for ( int i = 0; i < S.length(); i++ ) {
        int a = 0;
        for ( int j = 1; i-j >= 0 && i+j < S.length(); j++ ) {
            if ( S[i-j] == S[i+j] ) { a++; }
        }
        ans = max( ans, 1+a*2  );

        a = 0;
        for ( int j = 0; i-j >= 0 && i+1+j < S.length(); j++ ) {
            if ( S[i-j] == S[i+1+j] ) { a++; }
        }
        ans = max( ans, a*2 );
    }


    cout << ans << endl;

    return 0;
}