#include<bits/stdc++.h>

#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e5 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n;
string s;
map<int, int> f[4][maxN];
void ReadInput()
{
    cin >> s;
    n = s.size();
    s = ' ' + s;
}
int dp(int i, int l, int r)
{
    if(l >= r) return 0;
    if(f[i][l].find(r) != f[i][l].end()) return f[i][l][r];
    int& res = f[i][l][r];
    res = oo;
    if(s[l] == s[r]) res = dp(i, l + 1, r - 1);
    if(i < 3)
    {
        res = min(res, dp(i + 1, l + 1, r) + 1);
        res = min(res, dp(i + 1, l, r - 1) + 1);
    }
    return res;
}
void Solve()
{
    int res = dp(0, 1, n);
    if(res <= 3) cout << res;
    else cout << -1;
}
#define taskname "sol"
int32_t main()
{
    if (fopen(taskname ".inp", "r"))
    {
        freopen(taskname ".inp", "r", stdin);
        //freopen(taskname ".out", "w", stdout);
    }
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    //cin >> T;
    for(int itest=1; itest<=T; itest++)
    {
        ReadInput();
        Solve();
    }
}