#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define fs first
#define sc second
#define sz(x) (int)(x.size())
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<int, ll> pil;
typedef pair<ll, ll> pll;
typedef priority_queue <ll, vector<ll>, greater<ll>> pqmin;
const double EPS = 1e-16;
const int INF = 2e9;
const int MOD = 1e9+7;

const int p=1e5+5;

//int getpos(int idx,int i){
//    return idx+i-5;
//}
//
//int inversepos(int idx,int pos){
//    return pos-idx+5;
//}

void solve(){
    string s;
    cin>>s;
    int n=sz(s);
    vector<map<int,int>>dp(n);
    int ans=0;
    for(int i=n-1;i>=0;i--){
        for(int j=max(i,n-1-i-5);j<=min(n-1,n-1-i+5);j++){
            dp[i].insert({j,0});
            if(abs(i-j)<2){
                if(s[i]==s[j]){
                    dp[i][j]=abs(i-j)+1;
                }else{
                    dp[i][j]=1;
                }
//                cout<<"! "<<i<<" "<<j<<" "<<dp[i][j]<<endl;
                ans=max(ans,dp[i][j]);
                continue;
            }
            if(i!=n-1){
                if(dp[i+1].count(j)){
                    dp[i][j]=max(dp[i][j],dp[i+1][j]);
                }
            }
            if(j!=0){
                if(dp[i].count(j-1)){
                    dp[i][j]=max(dp[i][j],dp[i][j-1]);
                }
            }
            if(s[i]==s[j] && i!=n-1){
                if(dp[i+1].count(j-1)){
                    dp[i][j]=max(dp[i][j],2+dp[i+1][j-1]);
                }
            }
//            cout<<"! "<<i<<" "<<j<<" "<<dp[i][j]<<endl;
            ans=max(ans,dp[i][j]);
        }
    }
    if(n-ans>3){
        cout<<-1<<endl;
    }else{
        cout<<n-ans<<endl;
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int t=1;

    while(t--){
        solve();
    }

    cin.get();
    return 0;
}