const rl = require("readline").createInterface({ input: process.stdin });
var iter = rl[Symbol.asyncIterator]();
const readline = async () => (await iter.next()).value;

void async function () {
    // Write your code here
    let s = await readline()
    function isSecretStr(str) {
        return str == str.split('').reverse().join('')
    }
    let max = 0
    for (let i=0; i<s.length; i++) {
       for (let j=i+1; j<=s.length; j++) {
            if (s[i] !== s[j-1]) continue  // 首尾不相等，直接进入下一个循环
            let str = s.substring(i, j)
            if (isSecretStr(str)) {
                if (str.length > max) {
                    max = str.length
                }
            }
        } 
    }
    console.log(max)
}()