#include<bits/stdc++.h>
using namespace std;
using Int = long long;

template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
Int dp[1111][1111];
string s;
Int n;
// [l, r]
Int dfs(Int l,Int r){
  Int &res=dp[l][r];
  if(~res) return res;
  res=(s[l]==s[r])*(1+(l!=r));
  if(l+1<=r-1) res+=dfs(l+1,r-1);
  return res;
}

signed main(){
  cin>>s;
  n=s.size();
  Int ans=0;
  memset(dp,-1,sizeof(dp));
  for(Int i=0;i<n;i++)
    for(Int j=i;j<n;j++)
      chmax(ans,dfs(i,j));
  cout<<ans<<endl;
  return 0;
}