#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;}



struct RollingHash{
  using ull = unsigned long long;
  vector<ull> hash,p;
  RollingHash(){}
  RollingHash(const string &s,ull B=1000000007LL){
    int n=s.size();
    hash.assign(n+1,0);
    p.assign(n+1,1);
    for(int i=0;i<n;i++){
      hash[i+1]=hash[i]*B+s[i];
      p[i+1]=p[i]*B;
    }
  }
  //S[l, r)
  ull find(int l,int r){
    return hash[r]-hash[l]*p[r-l];
  }
};


//INSERT ABOVE HERE
signed main(){
  string s;
  cin>>s;
  int n=s.size();
  string t(s);
  reverse(t.begin(),t.end());
  if(s==t){
    cout<<n-1<<endl;
    return 0;
  }
  
  RollingHash rhs(s),rht(t);
  int ans=0;
  
  // odd
  for(int i=0;i<n;i++){    
    int l=0,r=min(i,n-(i+1))+1;
    while(l+1<r){
      int m=(l+r)>>1;
      auto x=rhs.find(i+1,i+1+m);
      auto y=rht.find(n-i,n-i+m);
      if(x==y) l=m;
      else r=m;
    }
    if(l==min(i,n-(i+1))){
      chmax(ans,l*2+1);
      continue;
    }
    int pl=l,pr=r;
    {
      l=pl;r=pr;
      int p=l;
      r=min(i,n-(i+2))+1;
      while(l+1<r){
        int m=(l+r)>>1;
        auto x=rhs.find(i+2+p,i+2+m);
        auto y=rht.find(n-i+p,n-i+m);
        if(x==y) l=m;
        else r=m;
      }
      chmax(ans,l*2+1);
      pl=l;pr=r;
    }
    {
      l=pl;r=pr;
      int p=l;
      r=min(i-1,n-(i+1))+1;
      while(l+1<r){
        int m=(l+r)>>1;
        auto x=rhs.find(i+1+p,i+1+m);
        auto y=rht.find(n-i+1+p,n-i+1+m);
        if(x==y) l=m;
        else r=m;
      }
      chmax(ans,l*2+1);
      pl=l;pr=r;
    }
  }

  // even
  for(int i=0;i+1<n;i++){
    if(s[i]!=s[i+1]) continue;
    
    int l=0,r=min(i,n-(i+2))+1;
    while(l+1<r){
      int m=(l+r)>>1;
      auto x=rhs.find(i+2,i+2+m);
      auto y=rht.find(n-i,n-i+m);
      if(x==y) l=m;
      else r=m;
    }
    if(l==min(i,n-(i+2))){
      chmax(ans,l*2+2);
      continue;
    }
    
    int pl=l,pr=r;
    {
      l=pl;r=pr;
      int p=l;
      r=min(i,n-(i+3))+1;
      while(l+1<r){
        int m=(l+r)>>1;
        auto x=rhs.find(i+3+p,i+3+m);
        auto y=rht.find(n-i+p,n-i+m);
        if(x==y) l=m;
        else r=m;
      }
      chmax(ans,l*2+2);
      pl=l;pr=r;
    }
    {
      l=pl;r=pr;
      int p=l;
      r=min(i-1,n-(i+2))+1;
      while(l+1<r){
        int m=(l+r)>>1;
        auto x=rhs.find(i+2+p,i+2+m);
        auto y=rht.find(n-i+1+p,n-i+1+m);
        if(x==y) l=m;
        else r=m;
      }
      chmax(ans,l*2+2);
      pl=l;pr=r;
    }
  }
  
  cout<<ans<<endl;
  return 0;
}