#include<bits/stdc++.h>

using namespace std;

#define F first 
#define S second 
#define pb push_back
#define int long long

const int lar=3e18;

string a;
int ans=0;
int gogo(int l,int r,int id){
    if(id==4) return lar;
    while(l<r){
        if(a[l]==a[r]) l++,r--;
        else{
            return min(gogo(l+1,r,id+1),gogo(l,r-1,id+1));
        }
    }
    return id;
}

void solve(){
    cin>>a;
    int ans=gogo(0,a.size()-1,0);
    if(ans<=3) cout<<ans<<"\n";
    else cout<<"-1\n";
}

signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    solve();
    return 0;
}