#include<iostream> #include<string> #include<algorithm> using namespace std; int getLen (string s, int l, int r) { while(l >= 0 && r < s.size() && s[l] == s[r]) { l--; r++; } return r - l - 1; } // 中心扩展法(单双中心取最大) int main () { string s; while (cin >> s) { int len = s.size(); if (len == 0) { cout << 0 << endl; continue; } if (len == 1) { cout << 1 << endl; continue; } int mS = 0; for (int i = 0; i < len - 1; ++i) { int m1 = getLen(s, i, i); int m2 = getLen(s, i, i + 1); mS = max(max(m1, m2), mS); } cout << mS << endl; } return 0; }