# include<iostream> using namespace std; bool a(string s){ for(int i=0;i<s.size()/2;i++){ if(s[i]!=s[s.size()-i-1])return false; } return true; } int main(){ string s1,s2; cin>>s1; int r=0,l=0,Long=0;//r开始，l长度，Long答案 for(r=0;r<s1.size();r++){ for(l=1;l<=s1.size();l++){ s2=s1.substr(r,l); if(a(s2)){ if(s2.size()>Long){ Long=s2.size(); } } } } cout<<Long; return 0; }