#include<bits/stdc++.h>
using namespace std;
 
int expandAroundCenter(string s, int left, int right)
{
    int n = s.length();
    while (left >= 0 && right < n && s[left] == s[right])
    {
        left--;
        right++;
    }
    return right - left - 1;
}
 
int longestPalindrome(string s)
{
    if (s.empty()) return 0;
    int maxLen = 1;
    for (int i = 0; i < s.length(); i++)
    {
        int len1 = expandAroundCenter(s, i, i);
        int len2 = expandAroundCenter(s, i, i + 1);
        maxLen = max(maxLen, max(len1, len2));
    }
    return maxLen;
}
 
int main()
{
    string s;
    cin >> s;
    cout << longestPalindrome(s);
    return 0;
}
//form bíp
 

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