#include <iostream>
#include <vector>
using namespace std;
int main() {
string str;
while (cin >> str) {
int n = str.size();
int maxD = 1;
vector<vector<bool>> dp(n,vector<bool>(n, false));
for (int i = n-1; i >= 0; --i) {
for (int j = i+1; j < n; ++j) {
if (j-i<=2) dp[i][j] = str[i]==str[j];
else dp[i][j] = str[i]==str[j]&&dp[i+1][j-1];
if (dp[i][j]) maxD = max(maxD,j-i+1);
}
}
cout<<maxD<<endl;
}
}

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